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Curtis B.
Curtis B., service manager
Category: Heavy Equipment
Satisfied Customers: 28936
Experience:  30 years exp. with diesel engines, heavy equipment and forklifts, including lp forklifts
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have mack truck all new power steering parts just wondering

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have mack truck all new power steering parts just wondering how too turn up flow on pump this is a rd688 model mack 1992 pressure is on close off at 2200 psi but flow rate isnt at what it should be .making steering alittle eratic at times hard and easy.did everthing possible with rh sheppard techs that rebuilt box only thing didnt do is turn up flow rate which they suggested i do which i never had too before so how would i do this on these kind of pumps .just what to be sure.on how too
I though some mack expert would have answered this! In my mind you need to understand that pressure is power and not speed. The pump volume is where the speed comes from. As pumps wear, they lose volume, and trying to adjust pressure up only makes it worse. If this pump is used on more than one function it possibly has a flow control on it. I'm thinking that all this pump does is the power steering and it is probably worn so it doesn't do its job.Probably need to rebuild pump or replace with new. Sorry.
Customer: replied 7 years ago.
pump is brand new pushing out 2200psi on close off but flow isnt were it should be they wont take back pump until i turn up flow but mack is mack wont tell me how this is done thanks

Find the flow control valve, it has to be part of the pump or in the pressure line coming out of the pump. It should have some access cover that will come off and give entry to an adjustment or valve. It can be screw adjusted or it could have shims. Maybe Mack could at least tell you if one is in system! Good luck.

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