Drawworks Cases: Drum & Brake System Protection

A drawworks is the one machine on a rig that directly governs drill string travel and hook load, and its component case has to hold three part families whose acceptance criteria have nothing in common. The drum grooving is judged on a single rule, that no raised impression may exist anywhere on the rope path. Brake rotors and band linings are judged on flatness and surface roughness. Gearbox, clutch and brake hydraulic parts are judged on fitted clearance and internal cleanliness. Those criteria also fail on very different timescales. A groove impression may only surface months later as uneven rope wear, a distorted rotor shows up immediately as judder and uneven braking force during tripping, and particle contamination in a hydraulic valve can stop the whole drawworks during commissioning. The core conclusion is that a drawworks case must be designed against four simultaneous constraints - zero raised damage on grooves and friction faces, rotating and precision mating parts restrained in their running attitude, brake hydraulic parts sealed in their own clean cavity, and large castings or forgings verified separately for lifting lugs and saddles. Define the component families first and the case second; putting a drum, brake band, gearbox and valve block into one cavity guarantees that at least one of them fails acceptance.

The delivery chain for drawworks parts is usually more involved than for ordinary industrial machinery. Components leave a factory or an overhaul workshop, travel by road to a rig builder or a port, cross climate zones by vessel or truck, then reach the wellsite over desert tracks or tidal flats, with repeated lifting and unpacking along the way. On that chain, almost every groove defect traces back to one mistake made between two lifts. Rotor flatness goes out of tolerance because of where the support points were placed. Gearbox and clutch mating faces leak because cavity humidity was left uncontrolled long enough to start corrosion. The sections below set out packing parameters, support and lifting schemes, cleanliness and humidity targets and arrival acceptance criteria for seven component families, written so they can be copied into a purchase specification by drawworks builders, workover and drilling contractors, and oilfield equipment managers.

Contents

• Scope Definition and Component Families for Drawworks Cases
• Drum and Grooving: No-Touch Face Identification and Saddle Design
• Drum Shafts, Bearing Housings and Couplings
• Disc Brakes: Rotor Flatness and Friction Face Protection
• Band Brakes: Bands, Brake Wheels and Adjustment Mechanisms
• Gearboxes and Clutches: Mating Faces, Oil Seals and Fitted Parts
• Brake Hydraulics: Cleanliness, Port Capping and Accumulators
• Large Castings and Forgings: Lifting, Saddles and Lug Selection
• Pneumatic and Electrical Components: Moisture, Vibration and Freezing
• Rust Prevention Graded by Storage Duration
• Liner Zoning, Weight Distribution and Shell Load Path
• Sealing, Pressure Equalisation and Humidity Records
• Marking, Packing List and Opening Acceptance
• FAQ
• Conclusion and Further Reading

Scope Definition and Component Families for Drawworks Cases

Scope definition, not liner design, is where drawworks projects lose control. The base frame, a complete drum assembly whose diameter and weight exceed normal case lifting capacity, the crown block frame and a one-piece reducer housing are over-limit items. They travel on dedicated saddles under protective covers and should never be treated as large items inside a case. Seven families genuinely suit a dedicated component case: drum grooving repair parts, brake rotors and brake hubs; brake band assemblies, brake wheels and linkage adjusters; gearbox internals, clutch plate packs and spline sleeves; brake hydraulic power units, valve blocks, cylinders and accumulators; pneumatic valves; electronic modules, encoders and limit switches; and pins, bearing housings and matched fasteners.

Three statements capture the method. First, group by acceptance criterion rather than by drawing level. A brake rotor and a brake valve block both belong to the brake system, yet one is judged on flatness and the other on particulate class, so a shared cavity forces a compromise that damages one of them. Second, group by whether the face can be repaired on site. Grooves, friction faces, threads and sealing faces cannot be restored in the field and need individual restraint, whereas coated surfaces, non-mating surfaces and exposed structural faces tolerate light scuffing and can share a cavity to reduce case count. Third, set corrosion and humidity class from storage duration, not from expected transit time, because the interval between dispatch and overhaul installation commonly runs from six to eighteen months and always spans at least one wet season.

Putting this family list and its acceptance basis into the purchase documents lets the supplier commit, at quotation stage, to which parts occupy which case and what each case must achieve, instead of reverse-engineering a liner at the end of packing production.

Drum and Grooving: No-Touch Face Identification and Saddle Design

The drum concentrates the highest value on a drawworks and is also the part most easily damaged by the packing method itself. The grooving is the rope's load path, and groove radius and pitch accuracy govern how the rope lays in multiple layers and how contact stress is distributed. Any raised impression makes the rope ride over a local high point, producing uneven wear and a disordered wrap, while a depression at a groove root lets the rope sink and disturbs the relationship between adjacent wraps. Both are unrecoverable in the field: restoring grooving means re-machining on a lathe or weld overlay followed by machining, which means the drum goes back to the works.

Saddle design is the heart of this section. The saddle must share the arc of the drum outside diameter, with a contact angle between 90 and 120 degrees and a soft facing, typically polyurethane elastomer at Shore A 80 to 90, so load spreads around the circumference instead of sitting on a few points. Support points belong at the two ends, close to the bearing housings, not at mid-shell, because the middle of the shell is exactly where the grooving is. Where case dimensions force mid-shell support, place the contact on an ungrooved transition section or on an end plate, and interpose a full sheet of soft material between the grooved section and the saddle. Never leave a timber member in sustained contact with grooving. Timber absorbs moisture and becomes a stable internal wet source, and as moisture content changes the support loses contact and the drum starts to move.

Protecting the grooved section itself matters equally. Cover the full grooved section with a conforming soft sleeve or a continuous non-woven sheet beneath peelable film. The cover exists to keep hard tools off the grooving, not to carry load, so thick stacked material is unnecessary and even counterproductive. Never face the grooving with sheet metal or hard corrugated board, both of which create hard point contacts. If a rope has already been fitted or a wrap test performed before dispatch, the grooving may carry grease and wire fragments; clean it and record the cleaning method before packing, so that residues do not cure over months of storage and turn into extra preparation work before start-up.

Drums normally ship with bearing housings, sleeves and seals, so manage them as numbered sets, keep matched parts in adjacent cavities and mark them with a common colour code. The crew can then lift parts in assembly order and spend less time searching, which removes a major source of secondary damage. For comparable drum and rope-handling parts, see Winch Parts Cases: Drum and Rope Component Protection.

Drum Shafts, Bearing Housings and Couplings

The drum shaft transfers torque from the gearbox to the drum, and both bearing journals and seal seats carry explicit requirements for dimensional accuracy, roundness and roughness. Shafts fail differently from drums: a drum suffers on its grooving, a shaft suffers from bending and journal scoring, so a support scheme designed for one cannot simply be applied to the other.

Three requirements govern shaft restraint. First, carry a shaft on two or more support points placed near the bearing journals but not directly on them, so contact lands on a shoulder or an unmachined section. Where a journal must take the load, use a matched-arc soft saddle with an inside diameter that fits without clamping. Second, apply axial restraint in both directions, with a fixed stop at one end and a compliant limit at the other, because a single-sided stop lets the shaft migrate along its axis until it strikes a cavity wall. Third, keep small and medium diameter shafts horizontal on multiple supports rather than standing them up or tilting them. Set support spacing from the length-to-diameter ratio, densify support points above a ratio of 30, and run a deflection check against the transport dynamic factor.

Bearing housings and bearings bring two requirements that are easy to overlook. Bearings, especially tapered roller and angular contact types, must not sit under axial preload for months. A clamped axial state during storage brinds false brinelling into the raceways, which then appears as vibration and noise in service. The housing should be fixed while the bearing stays restrained but unloaded. Journals and seal lip positions must never sit against a fibre-shedding material. Felt, cotton waste and ordinary corrugated board shed fibre under vibration, the fibre adheres to seal lips, and it is then carried into the lubricant cavity.

Couplings, spline sleeves and disc packs are matched sets, so they belong in one cavity arranged in assembly order. Where case zoning forces them apart, mark the pairing on the case and list it in the packing list; mixing matched transmission parts from different shipments loads the shaft line eccentrically and shortens bearing life. For matched-set handling of comparable rotating parts, see Brake and Clutch Assembly Cases: Friction Plate and Piston Protection.

Disc Brakes: Rotor Flatness and Friction Face Protection

Disc brakes provide the controlled braking and hook load holding used during tripping, and braking torque stability depends on friction face flatness together with parallelism between the two faces of a rotor. Once a rotor distorts, braking produces cyclic judder, fluctuating torque and local overheating. In transport, that distortion almost always comes from two sources: wrongly placed support points, and a storage attitude that leaves the rotor under sustained one-sided pressure.

Four requirements define the packing design. First, store rotors in the running attitude or upright, meaning the face vertical and the load taken by the hub or a purpose-made bracket. Laid flat, the friction face becomes a load-bearing surface, and self weight plus anything above it leaves permanent warping. Second, place supports on the hub or another rigid region of the wheel. Never put a support or a spacer block on the friction band. Where a spacer is needed simply to stop a rotor touching a partition, use closed-cell soft foam with minimal contact area. Third, fit a protection plate or a conforming soft cover over the friction faces. The plate itself must be rigid and flat, never a material that creases, and it should sit with a small uniform clearance so that its own distortion cannot press on the rotor. Fourth, never stack rotors against each other; give each its own cavity or an upright divider rack with a soft facing on the frame.

Rotors normally ship with calipers and friction pads. Friction material is property-sensitive: its coefficient of friction shifts with moisture, oil contamination and sustained pressure, so pack pads separately, away from oil and water, and never in a cavity containing greased steel. Sustained pressure plastically deforms friction material, so pads should not be clamped; give them a small amount of freedom within their pockets and soft limits around the edges. Mark pad and rotor pairings by set so that material from different batches is not mixed on site.

The hydraulic or pneumatic actuators on disc brakes are precision items with small piston-to-bore clearance, and their oil and air ports need the same capping discipline as the brake hydraulic section below. Keep them out of the rotor cavity.

Band Brakes: Bands, Brake Wheels and Adjustment Mechanisms

Band brakes serve as main or auxiliary braking on many drawworks, deriving torque from contact between band and wheel, with performance depending on the wrap arc and on an evenly distributed clearance. Two failure routes dominate. Friction lining changes its coefficient after exposure to moisture, oil or sustained pressure, and the brake wheel surface takes impressions or scores that create local high points in the contact.

Band packing turns on three negatives: no compression, no moisture, no oil. Store bands at their natural curvature. Never flatten a band or bend it in reverse, because the steel backing and the bonded lining will separate or crack at the interface. Hang each band or lay it on a formed cradle whose arc matches the band backing, so the lining face never acts as a bearing surface. Face the lining inward or downward to keep dust and liquid off it. Keep lining away from any oil-bearing material in the same cavity, including greased steel parts and soft PVC spacers that may release plasticiser, since the former migrates oil and the latter softens or swells the lining over months of contact.

Brake wheels and friction wheels are large thin-wall rotating parts with a higher distortion risk than rotors, because a thin shell laid flat and stacked easily loses its roundness. Handle them the same way as rotors: upright storage, support on the hub or a rigid end face, and a protection plate on the surface. Never use the cooling ribs or fins as support points; those areas are thin and deform readily.

Adjusters and linkages include turnbuckles, springs, pins and levers. They are small but they set the balance of the brake, so bag them by functional group and mark the adjustment position. Protect springs with a cardboard or plastic tube so they cannot be compressed to solid, which would change their free length. Match pins with their retaining clips in the same bag, and never let them rattle loose against each other. Clearance shims are thickness-graded parts, so bag them by thickness and label each bag; mixed shims lead to repeated dismantling and reassembly on site.

Where a band ships together with its brake cylinder, linkage and springs, do not reduce the packing envelope by compressing the assembly. A spring held at solid length takes a permanent set and changes the braking torque. Cylinders should be fixed close to their free or normal working position. For related packaging practice on hoisting equipment, see Hoist Component Cases: Drum and Brake Protection.

Gearboxes and Clutches: Mating Faces, Oil Seals and Fitted Parts

Drawworks gearboxes and clutches look robust and behave delicately. Mating faces, seal bores and bearing bores all carry flatness and fit requirements, and whether a joint uses sealant or a gasket, its sealing performance depends on even contact across the face. One badly placed support can introduce micro-plastic deformation near the split line, and the result after assembly is a slow weep that takes several rounds of dismantling to locate.

Three requirements apply to gearboxes. First, secure the housing in its design installation attitude, so that transport loads act in the same direction as service loads. Fit shaft extension protectors on input and output shafts, and never use a shaft extension as a support point or a lifting point. Second, cover mating faces, split lines and inspection covers with a rigid protection plate or conforming film over a soft pad, and never rest a mating face on a hard support block. Third, keep oil seals and their bores unloaded. Do not support the assembly on the face where a seal sits, and do not let another component press against a seal lip. Rubber takes a permanent set under sustained load, and the seal weeps after assembly.

Gearbox internals follow the same logic as shafts, with two additions. Ground gear flanks are no-touch faces. A dent on a flank becomes a pitting initiation site once the gears run, so cover flanks with protective film or a soft wrapper and never support a geared section on a bare steel V-block. Match the internal rust prevention to the parts list. Where the cavity was oil-filled before dispatch, state the oil brand and grade in the delivery documents and say whether it must be replaced on site. Where the cavity ships dry, use vapour phase protection and record the cavity humidity.

Clutch packing splits by type. Dry friction plate clutches must not contact oil or water and need the same separation from grease and moisture as brake pads, packed independently. Wet multi-plate clutch packs must not sit under sustained pressure, because friction plates deform plastically and change their friction characteristic. Springs, diaphragms and pressure plates are precision items that should be fixed within their pockets with limited travel, and a pressure plate face must not touch any hard object. For combined brake and clutch assemblies on construction equipment, see Brake and Clutch Assembly Cases: Friction Plate and Piston Protection.

Brake Hydraulics: Cleanliness, Port Capping and Accumulators

The brake hydraulic system releases and applies the disc brakes, and its blocks are usually cartridge or proportional valve designs with very small clearances, making them far more sensitive to particulate contamination than a general hydraulic system. Once particles enter in transit, the symptoms are spool sticking, sluggish brake response or failure to hold pressure. A drawworks with an unresponsive brake system cannot work at all, and diagnosis means dismantling stage by stage and flushing the circuit.

Express cleanliness against ISO 4406, with common targets near 18/16/13 for brake hydraulics and tighter figures for proportional and servo-class elements. The packing task is to keep the as-built class from degrading, which comes down to four measures. First, plug every opening that communicates with atmosphere: O-ring equipped metal or nylon plugs on ports, blind flanges with gaskets on flanged joints, and crimped plastic caps on tube ends. Log plug quantities against the drawing and issue a plugging schedule with the shipment. Second, place valve blocks and cylinders in a dedicated clean cavity lined with low-shedding closed-cell material. Felt, cotton waste and ordinary corrugated board are all unsuitable, and no rusty carbon steel or uncleaned casting belongs in the same cavity. Third, restrain hoses and accumulators in the correct attitude. A hose must not sit below its minimum bend radius, and accumulators need their charge pressure recorded and must be kept away from temperatures outside the permitted range. Fourth, sample particle counts after transport and compare them with dispatch data to decide whether flushing is needed, rather than installing and hoping system flushing will recover the situation.

Accumulators deserve separate emphasis. An accumulator is a pressure-containing component, and its transport condition, meaning whether charge pressure is retained and at what level, must follow the manufacturer's instruction and be recorded in the documents. Permitted conditions differ by pressure state, and both venting the unit and retaining full charge can create problems. Position accumulators where nothing can strike them directly, and support the shell at mid-body on a soft cradle rather than at the connection end, so that weld necks never see bending moment.

Cleanliness and rust prevention pull against each other here as well: heavy grease applied for corrosion protection turns into contamination at unpacking, while omitting protection for cleanliness invites rust after a condensation cycle. A washable protective medium, or vapour phase protection in place of contact oiling, resolves the conflict. For contamination control practice on comparable hydraulic closing systems, see Filter Press Cases: Plate and Hydraulic Closing Protection.

Large Castings and Forgings: Lifting, Saddles and Lug Selection

Drawworks families include a substantial number of large castings and forgings: brake hubs, brake wheels, gearbox housings, frame connectors and counterweights. Surface protection is rarely the difficulty with these parts; the load path is. Castings and forgings are strong in bulk, yet thin-wall housings, housings with machined faces and long-span castings can deform or crack under single point support or incorrect lifting.

The first principle of lifting design is to align lifting points with structurally stiff locations. Use the original lifting lugs on parts that have them, and confirm before the lift that lugs are free of cracks and deformation and that threads are sound. For castings without lugs, use calculated slings with corner protectors and place the points where stiffeners intersect or where wall thickness changes, never at the middle of a thin wall, near a machined face, or on the edge of an opening. Keep the angle between sling legs and vertical within 60 degrees; wider angles drive the horizontal component at the lug up quickly, and casting lugs are usually designed for vertical or near-vertical loading only.

Saddle design treats a casting as a beam with some flexibility. Support long castings at three points or more, avoiding machined and sealing faces. Support rings and large rotating parts on the hub or a rigid end face, never on a machined end face or the plane carrying a seal groove. Line saddle contact surfaces with a soft pad whose compression set is low, so that support does not disappear over months of storage. Where a large housing has a machined joint face, turn that face upward or toward free space inside the case so a protection plate can cover it without any support touching it.

Rust prevention must match the surface state of a casting. Apply different levels of protection to machined and unmachined surfaces: machined faces take anti-rust grease or vapour phase material under film, while as-cast surfaces with intact mill scale need only a peelable coating or vapour phase protection. For castings that arrive with rust, remove loose corrosion products and record the treatment, because loose rust becomes a particle source inside the case under vibration and threatens the precision parts sharing the shipment. Verify corrosion performance with the neutral salt spray method in GB/T 10125, taking time to red rust as the selection basis for coatings. For offshore platform drawworks parts, see Winch Parts Cases: Drum and Rope Component Protection.

Pneumatic and Electrical Components: Moisture, Vibration and Freezing

A drawworks control circuit contains pneumatic valves, solenoid valves, limit switches, encoders and electronic modules. They are small, expensive, and their failure decides whether the machine starts. Pneumatic items typically fail in transit through ice blockage and rust, as moist air gives up water at low temperature and the water then either freezes or corrodes. Electrical items typically fail through condensation-driven insulation loss and intermittent faults that only appear weeks after commissioning and are expensive to trace.

Three measures suit pneumatic parts. Fit dust caps on every air port, using caps with an elastomeric sealing feature rather than a plain plastic cover. Keep valve interiors dry, whether by dry air purging or vapour phase protection, and avoid greases that contaminate spools. Solenoid coils are moisture sensitive, so pack them separately and protect the terminals, and never press a metal component against a coil housing.

Electrical items need overlapping but distinct treatment. For moisture, use a composite inner pack of foil bag, desiccant and humidity indicator card to isolate modules from the case atmosphere, target below 40 percent relative humidity in the module cavity, and record desiccant quantity and indicator type in the packing list. For vibration, give limit switches and encoders, which contain fine moving or optical elements, a dedicated cut pocket each, using closed-cell foam of moderate density so the part is neither clamped nor free to move, and fit damper pads between case and pallet to attenuate road-borne high frequencies. For static, place MOS-containing modules in a shielding bag before they enter their pockets, line those pockets with a dissipative material whose surface resistivity falls in the 10^6 to 10^9 ohm band, cap every connector, and have staff wear a grounded wrist strap during unpacking.

One point deserves a warning. Pneumatic and electrical items both fail because of water, yet their temperature preferences conflict. Pneumatic valves risk ice blockage at low temperature, while electronic modules risk accelerated electrolytic capacitor ageing at high temperature, so the two should not share a humidity strategy or a cavity. Environmental test methods are described in the damp heat, vibration and shock sections of MIL-STD-810H, cited here as test method references only and not as a military certification.

Rust Prevention Graded by Storage Duration

Rust protection for drawworks parts cannot be covered by one figure across the whole shipment; it must be graded by material and storage duration. The purpose of grading is to spend money where failure actually occurs. Stainless and plated parts need almost nothing over short or medium storage, while carbon steel machined faces, cast iron and rusty castings differ enormously.

Four grades work in practice. Grade A, up to three months: a thin anti-rust grease film on machined faces with basic desiccant, suitable for spare parts installed on arrival. Grade B, three to six months: anti-rust grease plus film on machined faces, vapour phase material with desiccant in the cavity, relative humidity held below 55 percent. Grade C, six to twelve months: full vapour phase coverage, desiccant sized up for the net cavity volume, relative humidity below 45 percent, and an indicator card serving as the opening criterion. Grade D, beyond twelve months or multi-climate sea freight: grade C plus a vacuum or heat-sealed barrier inner pack, individual packing where warranted, and a recommendation in the delivery documents for intermediate inspection and desiccant replacement.

Material differences belong in the scheme as well. Stainless and carbon steel parts must occupy separate cavities. Free iron is a common cause of pitting in stainless steel, and tools or gloves that have handled carbon steel must not then touch stainless surfaces. Aluminium against steel needs a non-metallic barrier to suppress galvanic corrosion, and zinc-coated parts should not sit for long against copper alloys, where contact can produce electrochemical attack and discolouration. Vapour phase inhibitor formulations are material specific, so a chemistry suited to carbon steel is not automatically suited to stainless, aluminium, copper or certain plated finishes; check the compatibility statement before selection to avoid discolouration or dulling.

A note is warranted on how to use GB/T 10125 neutral salt spray testing. Test duration should match the actual exposure. Corrosion stress differs greatly between a coastal yard, an offshore platform and an inland enclosed warehouse, and defaulting every project to the longest duration raises cost noticeably without reducing risk.

Liner Zoning, Weight Distribution and Shell Load Path

Liner and shell form one system. Weight distribution across a drawworks shipment is extremely uneven, with a multi-tonne brake hub on one side and a few hundred grams of limit switch on the other. Design the liner merely to fill available space and the shell's real load points concentrate at one or two spots, so the floor and side walls see stresses well above the design case during lifting.

Four rules govern zoning. First, put heavy parts toward the middle and light parts toward the edges, placing the two heaviest items at the inboard ends of the length rather than in the corners so the centre of gravity sits near the geometric centre. Second, give each layer an independent load path, with upper weight carried by posts or partitions straight to the case floor instead of through the parts below. Third, separate clean, dry and structural cavities, keeping hydraulic, electrical and casting cavities unconnected and using continuous partitions rather than local patches. Fourth, keep long parts out of heavy-part cavities, so that bars, brake bands and heavy rotating parts never share a zone where a heavy item can bow a long one under braking shock.

Liner material follows contact stress and part weight. Closed-cell EVA, XPE and polyurethane foams are the usual choices: high density with low rebound for heavy castings, medium or low density with high rebound for precision electronic parts, and medium density with soft facings at the support points for long parts and shafts. Cut pockets with an assembly allowance, typically 1 to 2 mm, so parts drop in by hand without tapping. An over-tight pocket turns the liner into a clamp, and sustained clamping leaves impressions on thin-wall parts. For comparison of density, rebound and compression set across foam options, see Protective Case Foam Material Comparison.

Verify shell loading against three cases: static, meaning the packed weight; lifting, checked with a dynamic factor of 1.5 to 2.0 applied at the lifting points and floor; and transport shock, assessed against the worst condition in the actual logistics chain. Keep forklift pockets clear of lifting points and internal supports so that the two handling methods do not weaken each other. Where a component exceeds the case capacity, state at proposal stage that it ships on a dedicated saddle, and flag the split shipping arrangement on the packing list so no one on site reports a shortage.

Sealing, Pressure Equalisation and Humidity Records

The goal of sealing is a controlled internal environment, not a hermetically closed container. Drawworks cases routinely cross altitudes and climate zones, and a fully sealed non-breathing shell develops a pressure differential between inside and outside, which at minimum lifts the gasket and at worst distorts the lid and loads the hinges.

Gasket selection follows the environment. Silicone covers a wide temperature range with low compression set and suits inland and cold regions with large temperature swings, but tears relatively easily. EPDM offers good weathering and water resistance and suits hot-humid and coastal locations, though its oil resistance is limited, so assess compatibility where greased parts share the case. Polyurethane wears well but hydrolyses over time and is a poor choice as a primary seal in persistently wet conditions. Control gasket compression to the design value, commonly 25 to 40 percent; too little allows water past and too much accelerates permanent set.

Where transport involves significant altitude change, air freight or multiple climate zones, fit a pressure equalisation valve so gas moves in and out slowly while water and dust cannot pass. Mount the valve away from case faces that could pond water or accumulate dust, and keep it replaceable for maintenance. For valve selection and upkeep logic, see Case Pressure Equalisation Valves: Principles and Selection.

Humidity recording is where a drawworks case differs from a general industrial case. Drawworks parts are high value and inspection intervals are long, so a humidity indicator card read only at opening cannot show whether condensation occurred in between. For grade C and grade D storage, place a temperature and humidity logger or a maximum-minimum humidity indicator inside the cavity so that the record shows whether limits were ever exceeded. If the record shows the interior reached near dew point, inspect every carbon steel machined face in that cavity rather than only the outermost part. Size desiccant from net cavity volume and target humidity with a margin, and position the indicator card where moisture arrives first, usually near the lid edge and the base, rather than at the top. Hardware corrosion performance decides whether a sealing system survives its intended life; for selection and maintenance, see Toolbox Hinges, Latches and Seals.

Marking, Packing List and Opening Acceptance

Marking exists so that someone on site can judge condition and handling method without opening the case. Under GB/T 191 and GB/T 13384 the exterior should carry handling pictorial marks including this way up, keep dry, centre of gravity, lifting points and do not roll. A drawworks case needs further information: maximum single item weight, recommended lifting points, whether upright storage is required, and where the humidity indicator card is to be read first. Item numbers should correspond to drawworks drawing numbers, and every part inside should carry both its item number and its installation location so that the crew spends less time searching and handling.

The packing list is the acceptance reference document and should contain at least: item number and description, quantity, unit weight, cavity location, no-touch face notes, pairing relationships such as drum to bearing housing, rotor to pad, and coupling sets, matched fasteners and seals, plug count, rust prevention grade, desiccant quantity and type, indicator card type, dispatch cleanliness data for hydraulic parts, accumulator charge pressure records where applicable, and packing date and packer. A mismatch between list and contents is the main source of arrival disputes, so have a second person verify and countersign after packing is complete.

Run arrival acceptance as seven steps. Check shell appearance and handling marks for drop, puncture, water ingress and crush deformation. Read the humidity card or logger and record the values, inspecting cavity by cavity if colour has changed. Verify item counts and plug counts against the list, since a missing plug means an opening was exposed in transit. Focus on unrecoverable faces: drum grooving, rotor friction faces, band linings, gear flanks, sealing faces and threads. Apply the agreed sampling plan, written into the purchase documents using a recognised AQL approach, described in Custom Case Acceptance: AQL Sampling Methods. Record and reseal, re-protecting opened but uninstalled parts and logging opening and resealing times. Unpack hydraulic items in a clean area, re-plugging and recording the time if the circuit cannot be connected immediately.

Name the test references in the purchase specification: stacking and vibration under the GB/T 4857 and ISTA families, distribution cycle simulation under ASTM D4169, ingress protection to IEC 60529 or GB/T 4208, and salt spray to GB/T 10125. Test programme selection should follow the actual logistics chain, because an inland project dominated by road transport and an export project with sea freight and multiple transfers do not share the same vibration and shock conditions. For the logic behind programme selection, see ISTA Transport Testing Procedures: Selection and Execution.

FAQ

Q: Why can drawworks drum grooving not be supported on a timber baulk or a steel bracket?

A: Grooving is judged on profile accuracy, and any raised impression turns into a local high point under the rope, causing uneven wear and a disordered wrap. Restoring grooving means returning the drum to a lathe or applying weld overlay and re-machining, so it is not repairable on site. A timber baulk makes near-line contact with the groove surface, and the stress along that line under landing impact exceeds yield by a wide margin, leaving an impression that only becomes visible once the rope is fitted. Timber also absorbs moisture and becomes a stable internal wet source, and as its moisture content changes the contact opens up and the drum begins to shift. A steel bracket is worse, because grooving is usually surface hardened, giving high hardness with brittle edges that chip readily against a hard object. The correct method is a saddle that shares the drum outside diameter with a 90 to 120 degree contact angle and a Shore A 80 to 90 polyurethane facing, positioned at the ends near the bearing housings rather than at mid-shell. Where mid-shell support is unavoidable, land on an ungrooved transition section or the end plate and interpose a full soft sheet over the grooved section, then verify contact stress against the transport dynamic factor.

Q: What happens if brake rotors are laid flat and stacked in a case?

A: The immediate consequence is loss of friction face flatness and of parallelism between the two faces. Laid flat, the rotor face becomes a load-bearing surface; self weight alone is enough to warp a large diameter rotor, and the weight above adds a sustained bending stress that becomes permanent over months. A distorted rotor produces cyclic judder, fluctuating braking torque, local overheating and uneven pad wear during tripping. Tracing that fault means dismantling the brake and measuring face runout, and the downtime cost is far above the cost of improving the packing. The correct method is upright storage with the load carried on the hub or a rigid wheel region, a rigid flat protection plate over the friction faces with a small uniform clearance beneath it, and individual cavities or upright divider racks for multiple rotors with soft facings on the rack frame. Vented rotors need particular care so that no spacer presses on the vent slots. A split rotor with a separate hub may be stored in parts, but each part still needs contact at a rigid region, and where a rotor carries an integral ring gear or encoder ring, neither feature may carry any load.

Q: How should a brake band be stored, and can it be flattened to save space?

A: No, it must not be flattened and must not be bent in reverse. A band is a composite of steel backing and bonded friction lining, and its integrity depends on the bond between them. Reverse bending separates or cracks the lining at the interface, and the damage is usually invisible at installation, only appearing in service when lining material detaches during braking. Store bands at their natural curvature, carried on a formed cradle whose arc matches the backing so that the lining face never acts as a bearing surface, with the lining facing inward or downward to limit dust and liquid accumulation. Keep the lining out of any cavity containing oil-bearing material, including greased steel parts and soft PVC spacers that can release plasticiser, since grease contaminates the friction surface while plasticiser softens or swells the lining over months of contact. Where a band ships with its brake cylinder, linkage and springs, do not compress the assembly to reduce the packing envelope, because a spring held at solid length takes a permanent set and changes braking torque. Clearance shims are thickness graded, so bag and label them by thickness to avoid repeated dismantling on site.

Q: Can a gearbox weep really be caused by the way it was packed?

A: Yes, and the connection is consistently underestimated. Whether a gearbox joint uses sealant or a gasket, sealing depends on even contact across the mating face, and even contact depends on flatness. Rest a mating face on a hard support block during packing, or let a heavy part press on the housing, and the face takes micro-plastic deformation near the split line. After assembly the result is a slow weep that requires repeated dismantling and lost production time to locate, at a cost far above the packing improvement. Secure gearboxes in the design installation attitude, cover mating faces, split lines and inspection covers with a rigid plate or conforming film over a soft pad, and never let a mating face rest on a hard block. Fit protectors on shaft extensions and never use a shaft extension as a support or lifting point. Do not support the assembly on the face where an oil seal sits and do not let anything press on a seal lip, since rubber takes a permanent set under sustained load and the seal will weep afterwards. Where the cavity was oil-filled before dispatch, state the oil brand and grade in the delivery documents and note whether it must be changed on site.

Q: Can brake hydraulic valve ports be plugged with cotton waste or paper for the journey?

A: Not recommended, and on cleanliness-critical projects it should be prohibited outright. Cotton waste sheds fibre, which travels into a valve block and gathers at an orifice, producing spool sticking, sluggish brake response or loss of pressure holding. Paper absorbs moisture and creates a local rust site on the port wall, and on unpacking the rust travels into the circuit with the oil. Once a brake hydraulic system responds incorrectly the drawworks cannot work, and diagnosis requires staged dismantling and flushing at a cost far above the price of a plug. Use O-ring equipped metal or nylon plugs on ports, blind flanges with gaskets on flanged joints, and crimped plastic caps on tube ends. Log plug quantities against the drawing, list them in the packing list and verify completeness on arrival. Where temporary protection is unavoidable in transit, use a purpose-made elastomeric cap rather than wrapping threads in ordinary tape. Unpack in a clean, dust-free, wind-free area, and if the circuit cannot be connected immediately, re-plug the opening and record the time, so it is never left open to atmosphere.

Q: Should an accumulator be shipped pressurised or vented?

A: Both practices have their place, and the decision belongs to the accumulator manufacturer's instruction, not to the packing supplier. An accumulator is a pressure-containing component, and its permitted transport condition, meaning whether charge pressure is retained and what the maximum and minimum values are, along with any requirement for a dedicated transport restraint, is normally stated in the accompanying documentation. Venting without authority can cause abnormal bladder deformation under transport vibration, while retaining full charge can raise pressure beyond the permitted range in a hot environment. Verify the transport requirement against the documentation before packing, record charge pressure for each unit, and include the record in the packing list. Support the shell at mid-body on a soft cradle so that the connection end and flange never see bending moment or impact, and place the unit where nothing can strike it directly. The delivery documents should also state what to check on arrival, including appearance, fitting cap integrity, consistency of the pressure record, and whether recharging is required before installation. Where an accumulator ships with a valve block, put them in separate cavities so the accumulator cannot move against the block.

Q: Can pneumatic valves and electronic modules share one cavity to reduce case count?

A: It is not advisable. Both fail because of water, but their temperature sensitivities point in opposite directions, so a shared cavity creates conflicting control strategies. Pneumatic valves mainly risk ice blockage and rust, since moist air releases water at low temperature and the water then freezes or corrodes the internals, which favours a lower storage temperature and a drying medium. Electronic modules mainly risk accelerated electrolytic capacitor ageing and insulation loss at high temperature, while condensation creates leakage paths across circuit boards, so a module cavity must control humidity and also avoid heat. Pneumatic valves often contain copper alloys and plated parts whose compatibility requirements differ from the dissipative liner materials and desiccant types used for electronics. Keep the two cavities independent: hold the pneumatic cavity dry by dry air purging or vapour phase protection and cap every air port, and isolate electronic modules from the case atmosphere with a foil bag, desiccant and indicator card composite inner pack at a target below 40 percent relative humidity. Give fine mechanical items such as limit switches and encoders a dedicated cut pocket each with damper pads beneath.

Q: What surface preparation do large castings and forgings need before packing?

A: The method follows surface state and storage duration, but three requirements are universal. First, remove loose rust and residual moulding sand, because a rusty casting becomes a particle source inside the case under vibration and threatens precision valves and electronics sharing the shipment; record the treatment so it can be traced. Second, apply protection at different strengths to machined and unmachined surfaces: machined faces take anti-rust grease or vapour phase material under film, while as-cast surfaces with intact mill scale need only a peelable coating or vapour phase protection, which avoids spending machined-face money on rough surfaces. Third, keep both lifting and support away from machined faces. Place lifting points at stiffener intersections or other rigid regions and never at a thin wall or near a machined face; line saddle contacts with soft pads and keep them clear of sealing faces and fitted bores, using three points or more for long castings and carrying rings on the hub or a rigid end face. For castings stored beyond six months, raise the rust prevention grade, fit a humidity indicator card, and verify coating performance using the neutral salt spray method in GB/T 10125.

Conclusion and Further Reading

Related Reading

• Winch Parts Cases: Drum and Rope Component Protection
• Logging Winch Cases: Drum and Brake Protection
• Brake and Clutch Assembly Cases: Friction Plate and Piston Protection