Overhung load adaptors, inset, help ensure the life and reliability of hydraulic pumps in Roadtec's asphalt repaving machines, such as this RX 50B, their largest.To ensure smooth, trouble-free operation of the auxiliary hydraulic systems, two overhung load adaptors (OHLAs) from Zero-Max, Inc., Plymouth, Minn., are employed — one mounted on each side of the engine. OHLAs contain heavy-duty bearings that accommodate side load often present in belt drives. Eliminating side load at the pump shaft can increase pump life and performance. In the RX 50B, one OHLA transmits power to the pump supplying the components that move the ground asphalt to the conveyor. A smaller OHLA drives a hydraulic pump for steering, discharge conveyors, and auxiliary functions.
Chris McSharry, design engineer for Roadtec, reports, "Without the overhung load adaptors, too much stress was transmitted to the pumps' bearings, which could result in premature and costly pump failure." The drive setup McSharry and the Roadtec engineers devised positions the OHLAs 180° from each other. This balances the force applied to the front of the engine's crankshaft.
"The OHLAs give us a solid, permanent mounting surface, which aids in the overall stability of the system," adds McSharry. "By eliminating the stress and overhung loading, both the pump and bearings perform nicely without any threat of failure. The entire drive system runs more freely with the OHLAs and with less power utilized. These cold planers put out a lot of power, so the added stability from the OHLAs really promotes a smoother operating system."
Sensor is ideal for short strokes