EN
Core Selling Points
· Module 8, 20 deg pressure angle - the rack module used on standard rack-and-pinion construction hoists.
· Length matched to the 1508 mm mast section: 1508 / (pi x 8) = 60.0 pitches, so the tooth spacing continues across every section joint.
· Hardened tooth flanks on a tough core for the repeated start-stop loading of a hoist.
· Bolt hole pattern and end-pitch position machined to the mast section drawing.
Application Scenarios
· Passenger and material construction hoists (builder hoists)
· Rack replacement during mast inspection
· Mast climbing work platforms and transport platforms using module 8 drives
· Industrial lifts with rack and pinion drive
A construction hoist climbs its own mast. Each mast section carries one rack, and the drive pinions and the safety device pinion all run on that same rack. Because the mast is a stack of sections, the rack is a stack of short racks. If the tooth spacing does not continue correctly across each joint, the pinion hits the first tooth of every section.
The 1508 mm section height is not arbitrary. With module 8 the pitch is pi x 8 = 25.133 mm, and 60 pitches come to 1507.96 mm. A 1508 mm section therefore carries a whole number of teeth, and the joint pitch is held by the position of the rack on the section, not by trimming teeth.
We machine the rack teeth, then the bolt holes, from the same datum so that the first tooth sits at the same distance from the mounting holes on every rack. That is what keeps the joint pitch consistent when racks from different batches end up on the same mast.
| Item | Value |
| Module | 8 |
| Pressure angle | 20 deg |
| Pitch | 25.13 mm (pi x 8) |
| Teeth per 1508 mm section | 60 |
| Tooth depth (ISO 53 basic profile) | 18 mm (2.25 m) |
| Material | C45 / 40Cr / 42CrMo (to drawing) |
| Heat treatment | Tooth flanks induction hardened (hardness to drawing) |
| Cross-section and hole pattern | To mast section drawing or sample |
| Surface | Black oxide, painted or as specified |
Rack on a 1508 mm mast section and its engagement with a 15-tooth module 8 pinion
· Send the mast section drawing or a sample rack: we copy the cross-section, hole positions and the distance from the section end to the first tooth.
· Fasteners on hoist racks are normally property class 8.8; use the torque in your hoist manual.
· Check backlash and roller wear when fitting new racks - a new rack does not correct worn guide rollers.
· Whole-pitch geometry checked on every rack, not just on samples.
· Tooth and hole positions machined from one datum.
· Copy service from drawing or sample for older hoist models.
· Matching drive pinions supplied (see module 8 hoist pinions).
Applicable Industries
Building construction, hoist manufacturing and rental, bridge and tower construction, industrial lifting equipment.
For drawings, samples or a quotation, send us your rack, pinion or gear specification and quantity.
