The best time to determine the maintenance and reliability objectives for a piece of hydraulic equipment, and by extension, its life of ownership cost, is before it is purchased. And there are a couple of different ways this objective can be achieved.
Hydraulic equipment users who are sophisticated in their maintenance practices can dictate specific requirements for those variables known to influence service life, reliability and ongoing maintenance costs. For example, contamination control targets can be clearly defined in advance, and the machine manufacturer required to deliver the machine equipped with appropriate filtration and/or exclusion devices to achieve these targets.… continue reading »
One of our members described the layout of a rear-mounted knuckle crane on a truck, which was giving trouble, as follows:
“The pump is a bent axis Muncie pump 20 GPM, 4300 PSI. The pressure line is 3/4″ hose and steel tube. The pump intake line is a 2″ suction hose from the tank located on the crane base to a 1-3/4″ steel pipe under the truck bed and back up to a 2″ hose between the steel pipe and pump. Total length of each line (pressure and intake) is 33 feet. The intake line also features one, 45-degree fitting … continue reading »
The charge pump on a closed-circuit, hydrostatic transmission has a number of important functions. These include:
1. Replenish fluid lost from the transmission loop due to volumetric inefficiency of the pump and motor.
2. Replace fluid purged from the loop via the hot-oil flushing valve (where fitted).
3. Supply make-up fluid to compensate for load-induced oil compression and conductor (pipe/hose) expansion in the transmission loop.
4. Provide a flow/pressure source for activation of pump servo controls.
5. Provide a flow/pressure source for auxiliary functions such as parking brake release and pilot controls.
6. Maintain sufficient pressure on the low side … continue reading »