FRICTION CRANES SHOES

Just in! Cranes that have internal expanding friction clutches and Lattice Booms were commonly referred to as “Friction cranes” by the Standard writers and the Manufacture themselves. Nowadays, the Clutch type drums on the new lattice boom cranes are being replaced with Hydraulic Winches. So, these crane types are currently being named “Conventional cranes” (I wonder what an un-conventional crane is).

A hydraulic winch on lattice boom crane is nothing new; I worked on one in 1962 at Cape Canaveral, a 100 ton Bucyrus Erie with a hydraulic winch and a Triangular boom. But, with the demands of modern cranes the hydraulic winch has advantages, one thing, less moving parts subject to fatigue.

The photos following show a broken friction shoe on the main hoist of a Link Belt crane. This is the “power down side”, and if you think about it is actually being “pulled” when working due to its job of slowly lowering a weight against gravity.

When it failed the load was still controlled because the other side was engaged but, the operator recognized something went wrong by the vibration he felt in the crane. He set the load on the ground and went back to look and this is what he found!

Inspection of the Frictions clutches is as follows;

1. Lining thickness
2. Contamination from oil or water
3. Evenness of drum surface and contamination
4. Proper adjustment
5. Observe operation for smooth engagement
6. Visible damage or cracking of shoes
7. All pins, springs and keepers in place
8. Evidence of overheating of any component
9. Other noticed problem observed during operating under functional load test

Well this one got away, but now I look closer at this area of the shoe for “hammering” and cracking, so should you?