Sheppard gearbox pump pressure upgrade question

[bryanhes]

I am getting ready to change out my power assist steering in my 4905 for the Sheppard gearbox. I currently have the 1500psi pump but need to go to 2000psi for the Sheppard.

I was told that I do not need to change the pump out but could change out I think he called it a pressure spring?

Anyone have any idea about this? Maybe a kit or part # to do this without changing the pump completely.

Thanks,
Bryan

[TomC]

I had to do the same thing on my bus when changing from air assist to Sheppard.  The pump was putting out 1500# of pressure and it wasn't enough pressure to be able to turn the steering wheel when stopped.  I had them install a new pump with 2200# pressure and presto have finger tip steering.  Don't fool around-just get the proper pump and be done with it.  Good Luck, TomC

[Barn Owl]

Nimco has good used take-offs at great prices.

[bevans6]

I have a tag-on question to this issue.  My MC-5C originally had the power assist steering that had a ram connected to the pitman arm.  It was upgraded while in original service to what I think of as "integral" power steering, and what I think others refer to as Sheppard power steering.  The steering works pretty good but is quite heavy when the bus is stationary, it really won't turn the tires when they have full weight on them and the bus is stationary.  Would the pump supplied as stock with the ram type power assist steering have the same low pressure issue as is discussed here?

Brian

[TomC]

If you cannot turn the steering wheel when stopped with a Sheppard steering box, you need to up your pump pressure.  The hydraulic power steering pumps are not all that expensive.  Vickers makes a good one.  You want at least 2000 psi-mine is 2200 psi and is finger tip whether rolling or stopped.  I also use 15w-40 engine oil in it. Good Luck, TomC

[bryanhes]

I found the 1500 to 2000 psi relief valve. I also have another question in changing this over.

I was told that I should change the fluid to the same as what i am running in the engine in case the seal that drives the pump should fail. And if I get that into my engine it could wipe out the bearings.

If so do I just drain the reservoir and refill with the oil I am using and do this a couple times to flush out the old fluid?

Thanks,
Bryan

[bryanhes]

So has anyone changed the fluid from one type to another on sheppard power steering?

Bryan