Can the case ride the ladder rail?

Answer: No. The rail and arrester are built for 100 kg of person and lock at 6 kN, so a 35 kg case trips it.

Can two people carry 35 kg through the 600 × 1200 door?

Answer: Yes, tilted. At 20 degrees the 560 mm width projects to 500 mm and the front carrier walks backwards; past 30 degrees the wrench slides 8 mm.

Why a 60 degree sling angle?

Answer: It balances leg load and hook position: 99 N per leg at 60 degrees with hooks inside 320 mm, 121 N at 90 degrees.

Why rate the fall anchor at 12 kN for a 35 kg case?

Answer: 12 kN is the personnel-anchor figure, and using it keeps a platform post from bending in a fall. Over 0.6 m the case only develops 4.1 kN.

Can the wall drop to 5 mm?

Answer: It saves 1.2 kg, but deflection of the 560 mm face rises from 2.1 mm to 3.4 mm and the lid presses on the tools. Trim rib height first.

Tower Tool Case

Quick answer: A tower tool case splits into two routes: a 35 kg main case rides four lid eyes at a 60 degree sling, while a 12 kg sub-case climbs on one hand.

Thirty-Five Kilos Is a Route Decision
Four Eyes in the Lid, Sixty Degrees Apart
The 600 × 1200 Door Sets the Envelope
An 18 kg Wrench in Two Layers
Fall Arrest: Anchor, Lanyard, Drop
FAQ

1. Thirty-Five Kilos Is a Route Decision

A 110 m tower has 36 ladder sections of 3 m, and an empty climb takes 14 minutes. With a 35 kg tower tool case on the back the same climb runs 41 minutes, and every step past the third section needs the cage for balance. Site rules hold a one-person load at 20 kg, so the main case goes up on a hoist and the technician takes the ladder.

The 35 kg is a sum, not a round number: an 18 kg hydraulic wrench, 6 kg of reaction arm and sockets, 4 kg of hand tools, 3 kg of fasteners, 4 kg of shell. It is also the 17.5 kg per person two carriers manage across a sill; add a torque multiplier and 42 kg makes a two-person door pass awkward.

2. Four Eyes in the Lid, Sixty Degrees Apart

The eyes sit in the lid rather than the corners. Tools come out from above, the load sits high, and hoisting through the lid puts the cover in compression, so latches are never pulled open in flight. Each eye is an M10 stainless insert, 14 mm deep, 9.5 kN pull-out, rated 2.4 kN.

Tower tool case foam routed on a workshop table, black sheet laid flat, two workers stacking cartons behind a blue mesh fence

Sling angle decides what each leg carries. At 60 degrees the four-leg factor is 1.16, so 35 kg puts 99 N on each leg; at 90 degrees the factor climbs to 1.41, or 121 N. What sets the rating is a snag: a leg caught on grating while a 0.5 t winch keeps pulling loads the case to 1.2 kN, and the 1.6 kN webbing parts before the 2.4 kN eye does.

Geometry constrains it too. At 60 degrees the legs project inside a 320 mm square on the lid and the hooks clear the latches; at 45 degrees the projection grows to 380 mm and the hook body rests on the rim.

3. The 600 × 1200 Door Sets the Envelope

The tower door is nominally 600 × 1200 mm, with a 200 mm sill and a 100 mm cable tray 300 mm inside. Stack the three and the envelope that still passes on its side is 560 × 380 × 260 mm. Twenty millimetres of width is clearance for the gasket; the 260 mm thickness answers to the ladder cage, 700 mm clear inside, where a case thicker than 280 mm catches when the climber turns.

Carrying mode	Load limit	Centre of gravity	Through the door	Where it is used
One hand, sub-case	12 kg	150 mm	Vertical	Full climb
Shoulder, sub-case	16 kg	190 mm	Tilted 15°	Short sections
Two people, main case	35 kg	175 mm	Tilted 20°	Base to first platform
Hoist, main case	35 kg	175 mm	Straight up	Any height

With the envelope fixed, ribs can be placed: three vertical ribs at 140 mm spacing and 6 mm height stiffen the 560 mm face, two horizontal ribs line up with the internal shelf, and corners take an R25 radius.

4. An 18 kg Wrench in Two Layers

An 18 kg wrench in the base means lifting 18 kg out of a 260 mm well with one hand, which nobody does on a platform. The case splits it: the 12 kg body sits in a top socket, the 6 kg reaction arm goes below, and the tool used three times a shift ends up nearest the lid.

Layer	Item	Unit weight	Use per shift	Covers the layer below
Top left	Wrench body	12 kg	3 or more	Yes, lifts out
Top right	Four hand tools	4 kg	1 to 2	No
Base left	Reaction arm, sockets	6 kg	1	Covered
Base right	Fasteners, shims	3 kg	Weekly	Covered

Tower tool case shells moulded in an injection shop, yellow steel gantry over machines under a blue production-area sign

The centre of gravity rises with that layout: 175 mm above the base on a 380 mm wide case, tipping at 47 degrees. Move the body back down and the figure falls to 120 mm and 58 degrees, at two bends per use. On grating the case sits flat, so tilt only matters in a carry across a sill, under 15 degrees.

The hinge stops at 105 degrees, and holding the lid anywhere in that arc by its own weight takes 40 N. A 60 N strut lets one hand push the lid to 90 degrees while the other reaches in. Oversize it and an empty case rocks back 12 degrees under 80 N.

5. Fall Arrest: Anchor, Lanyard, Drop

Fall arrest is the second line, never the main sling. Each side of the case carries a ring rated to the same 12 kN as a personnel anchor, and the lanyard is 0.8 m with a double hook. A 35 kg case on a 0.6 m drop develops about 4.1 kN, well inside 12 kN, so the weak link stays on the case side.

Load-bearing part	Specification	Rated load	Safety factor	Inspection
Lid eye	M10 insert, 14 mm deep	2.4 kN	4	Quarterly
Side ring	Stainless, welded both faces	12 kN	5	Annually
Lanyard	0.8 m, double hook	8 kN	6	Each use
Platform post	Existing structure	12 kN	—	Annually

Drop distance sets the shock. With 0.8 m of lanyard and a 0.12 m pack, 35 kg lands at 4.1 kN; stretch the lanyard to 1.5 m and the figure reaches 6.8 kN, enough to deform the hook springs. Delete the pack and the same fall doubles past 8 kN.

Anchor position matters as much as rating. On a platform post the case swings inside the post line and never blocks the hatch; on a guardrail it swings 400 mm out and sits across the ladder exit.

Conclusion

Four numbers define what a tower tool case may do inside a tower: 35 kg on four lid eyes at 2.4 kN with a 60 degree sling, a 12 kg sub-case on one hand, a 560 × 380 × 260 mm envelope through a 600 × 1200 mm door, and a 12 kN ring taking 4.1 kN on a 0.8 m lanyard. One rule sits above them: a ladder carries one case at a time.

This article covers case-side specifications and design implications only, and does not address any handling, loading or use of the contents.