Our technician made a field service visit to a farm west of Wooster to check out a truck in need of repair.
We discovered the Dynapower pump and motor were in need of repair so the owner brought the truck to Wooster Hydrostatics where we removed the pump along with the Vickers pilot-operated charge relief valve.
We rebuilt the pump, and our customer provided a replacement Dynapower motor.
To assure a solid repair and future performance, we also installed a Sundstrand direct-operated charge relief valve, a cooler with a 12-volt DC motor and a return oil filter. We combined the case leakage flow from the pump and motor with the discharge oil from the charge pressure relief valve so that both flows are routed through the cooler and filter. The oil cooler was fitted with a 140°F temperature switch to operate the fan motor. A tube was installed on the motor case drain port to retain oil in the motor housing for bearing lubrication.
The hydraulic system was started on a Friday with charge pressure at about 400 to 425 psi and we were able to obtain about 2000 psi working (system) pressure. Our customers picked the truck up Monday morning and returned the truck to service. We then turned to repairing the Dyna Power pump and motor for their use as spare units.
Our focus is on returning machinery to our customers’ service – quickly — and, whenever possible, at a better and more reliable performance level.