D motor grader

Toms trucking · Oct 5, 2016

Looking for info on rebuilding the hydraulic pump on my d motor grader . I put a gauge on it and it's only putting out 700 psi. the book says the bypass valves don't open until 1400 psi. but it does not tell the pump pressure or gpm. There are 3 numbers on the pump they are 70078180 Kk30402 and 1512c3c1 can anyone tell me the pressure and gpm of this pump also is there a rebuild kit available for it. This machine has hydraulic blade,hydraulic side shift ,hydraulic turntable,hydraulic tilting wheels and we just installed a mid 70s Chevrolet power steering box on it that we are trying to run off the same hydraulic pump. I'm not sure if this little pump can effectively run everything , might need a bigger pump? Looking for some input I know some people have already been down this road Thanks Also looking for a parts manual for this machine I believe it to be a 1956 it was a gas machine converted to a 262 Buda diesel thanks again for any info.

JMS/.MN · Oct 6, 2016

I have no idea on pump specs, but if you"re adding power steering, you should add a priority valve to feed the PS. That pulls enough flow to keep the steering operable, despite other hyd draws. Salvage yards are a good choice for findingthem reasonable. I"ve gotten some off of IH combines.

old · Oct 6, 2016

Well if the relief valve opens at or should open at 1400PSI that should tel you that the pump should produce at a min. 1400PSI. The problem with a power steering pump is it is belt drive and also has a very small resevor (sp) so you almost cannot have enough fluid to do much.

I have used power steering ump for hyds in the past and they do work okay but all I had was one or 2 small cylinders so did not need a lot of fluid

JF in MI · Oct 6, 2016

I did the same thing; added a mid 70's power steering box to a D grader. Fluid flows through the box first, before going to the hydraulic control valves. Even if it didn't those other hydraulic operated items are only operated momentarily and not always while "on the move". The issue I was nervous about is that (a normal operating pump) puts out a lot more pressure than the steering pump the box came from. Also the inlet and outlet of the box are comparatively small and was worried about fluid overheating. Box worked perfect and while the fluid does get hot fast it is not excessive.

D motor grader

Toms trucking

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JMS/.MN

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old

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JF in MI

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