L&H Industrial recently submitted a new innovative design for the 2nd generation Straddle Mount Front Idler for electric rope shovels. This second generation straddle mount design has now accomplished the goal of removing the inner thrust plates and moving all the thrust surfaces outside the crawler frames. It accomplishes this by utilizing a key to carry torque between the idler wheel and the shaft, and a three-piece retaining plate to couple the wheel and shaft axially. The take up block is used, but now has a dedicated lube port for the thrust bushing. The bearing take up blocks are also reversible so that once the bushing has been worn on one side, it can be indexed 180° to use the opposite surface.
As with the first generation, a lube shield consisting of angle iron is incorporated to protect the lube ports from any debris. The thrust surface consists of a 1 ½” thick plate (different materials available) with lube grooves and a dedicated lube port. The retaining nut will rotate about this surface since it will be rotationally coupled to the shaft via the locking key. A specialty seal allows for significant run out as the bushing wears and will seal along the OD of the retaining nut. This seal is intended to allow the grease to purge and keep debris out which should extend the life of the thrust surface. Like any other straddle mount design, it is always ideal to keep the axial end play at a minimum. This design has 4 ports to probe the thrust surface to determine whether the assembly needs adjusted without removing any components. If adjustment is necessary the locking key can simply be removed, the retaining nut tightened, and the locking key replaced.
Unique Features of This Design
- Thrust washers can be replaced without splitting the crawler tracks.
- Wear in the thrust washers can be monitored through inspection port in outer thrust plate.
- The outer thrust plate is sealed and has a dedicated grease port.
- The end play in the shaft can be removed by adjusting the threaded nut at the end of the shaft.
- Use of retaining plate and key as locking devices to prevent axial and rotational movement of idler on shaft.
- Segmented retaining plate to allow for installation and removal.