Re: 350 Utility hydraulic troubles...

Posted by dick on June 05, 2003 at 08:45:29 from (67.31.150.27):

In Reply to: 350 Utility hydraulic troubles... posted by Steven@nd on June 04, 2003 at 16:38:17:

Assuming "engine pulls" means it's under load and absent gross external leaks in your hydraulic system, your problem is most likely in the pressure regulating/safety valve, located next to the reservoir in the rear gang of valves. What you have now is a continually loaded hydraulic pump which is deadheaded (i.e., producing maximum pressure) when none of the control valves is active; when you activate a valve to run the lift up and down, most of the hydraulic fluid has some place to go, the hydrualic pressure is much lower, and consequently the engine isn't working nearly as hard.

Inside the regulating/safety valve is an orifice which provides a small amount of flow to the hydraulic control circuit. Hydraulic pressure downstream of the orifice allows the output of the hydraulic pump to circulate back to the reservoir at low pressure, unloading the pump - this is not happening in your system. The way it's supposed to work is that when a control valve is activated, pressure in the control line drops, the hyraulic fluid is directed to the proper cylinder rather than back to the reservoir, and the hyraulic pump supplies the pressure needed (up to the maximum 1200 psi or so limited by the safety valve) to lift the load.

When the orifice which supplies pressure to the control line gets plugged, there is never any pressure in the control circuit downstream of the orifice, and the hydraulic pump is continually loaded. As a result, a high percentage of the engine's power ends up going into the hydraulic system, and the hydraulics end up getting very hot. The life expectancy of the pump is also very short under these conditions. I'd strongly suggest you fix this promptly and not use the tractor until then. Good luck, and email me if you'd like more information.

Follow Ups:

• Re: Re: 350 Utility hydraulic troubles... Steven@nd 15:46:12 06/07/03 (0)

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