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Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 5183
Experience:  17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
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I have a Volvo L50B SN: XL50BP9413X that has low torque to

Customer Question

I have a Volvo L50B SN: XL50BP9413X that has low torque to the wheels, and moves slowly when going up hills. The hydrostatic motor, pump, hydraulic pump, and gear pump have been gone through by a hydrostatic shop. The forward/reverse solenoids on the hydrostatic pump are new also. The manual calls for 6177 psi at the MA and MB ports on the hydrostatic pump, but I only have 5800 and 6525 psi at the two ports. Is there any additional adjustments that could be made, or any common problems of this nature? Would You recommend checking anything in specific or changing any specific parts?
Submitted: 1 year ago.
Category: Construction and Road Equipment
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 1 year ago.
I messed up the previous description. The pressures are 5800 and 5626, with 6177 being the pressure it is supposed to be at.
Expert:  Bradley Martin replied 1 year ago.

this article from a past customer with the issue you are having should help if it does not let me know

Customer: replied 1 year ago.
The URL you provided does not work, but I think I know what discussion you are talking about. I have already looked at the discussion regarding the L50B in which Dan was the answer expert. My question was regarding the hydrostatic side of the drive system, and what I might do with low pressure problems. I know that Dan said to look at the gearbox oil levels, and check pressures there. I did so a long time ago, and yes I will do so again. Dan also mentioned that the high low solenoid on the gearbox could be bleeding pressure off the hydrostatic system, which I don't understand because the systems are not linked. I guess he may have been talking about the forward reverse solenoids on the hydrostatic pump. I have issues with pressures below the specified amount on the hydrostatic pump, and I checked the clutch pressures in the gearbox. Dan mentioned relief valves that could be bleeding pressure in the pump, but I wondered what your experience with the machines was. I was wondering if you had additional thoughts on what may be causing my pressure loss.
Expert:  Bradley Martin replied 1 year ago.

does this model have joysticks or levers?

Expert:  Bradley Martin replied 1 year ago.

also does this model have a high speed switch? seems to me it may be stuck in high speed

Customer: replied 1 year ago.
The machine has separate levers for the tilt and lift for the loader. The controls for the two speed transmission are on the column by the steering wheel. That control is a handle for forward and reverse, and it is spun to select low or high speed. The loader does have a high low solenoid on the gearbox, but it shifts out of low and into high when driving it. You can feel the shift. It is possible that it may be stuck in high speed. Do you know a way of checking it? Also, do you know if the low hydrostatic pressures could cause the problem? Thanks
Expert:  Bradley Martin replied 1 year ago.

does this model have a two speed solenoid near the hydrostat if it does should be able to pull the coil off and check the valve to make sure it is moving properly and have you tries adjusting the pressure relief valve to raise the pump pressure up

Customer: replied 1 year ago.
It does not have a high low solenoid on the hydrostatic system, but does have one on the gearbox. The gearbox solenoid is operating as we could feel it moving. I adjusted the pressure cut off on the hydrostatic pump, but I was not able to attain the correct pressure. Do you have experience with these machines? If not, is there an associate of yours that would?
Expert:  Bradley Martin replied 1 year ago.

I will opt as I could not find my manual on this machine hope you are able to fix your issue sorry I could not help.

Expert:  Dan replied 1 year ago.

Hi Bryce, My name is***** will be glad to help. I worked at a Volvo Dealer in the past. First, the Hydraulic shop is responsible for calibrating the pump and drive motors so they should at no charge to you come out and stand behind their work and set up the pumps and if spec can not be obtained they need to pull them back off and see what they missed when they had them apart. Hopefully it is just an adjustment. Be sure there is no metal in the filter from the prior failure as i am assuming you flushed out the entire system? If not there is a potential that contamination in the system caused a problem with the rebuilt components and the shop will try to argue covering warranty. Let me know

Customer: replied 1 year ago.
The shop rebuilt the major components of the pump, but they did not replace all parts. The shop did not reman the parts, they rebuilt them. I pulled the components out initially, and I would have to pull them again if I wanted the shop to look at the pump. No we did not flush the system, only the hoses between the pump and motor. The shop found no contamination or excessive wear in any of the components anyway, so there was nothing to flush out of the system. My question is if you have any experience with common components that would cause pressure loss on this pump or system. Have you heard of the relief or pressure retention valves failing, or do you know of a way to test them? Does the control unit operated by the solenoids bleed pressure by if worn? Or maybe I am looking at the wrong part altogether, and I should check something else? Please let me know.
Expert:  Dan replied 1 year ago.

Thanks for the info. What are the details of the original problem, chain of events, findings and symptoms that lead up to the disassembly and repair of all these components? Also, You mentioned you had seen the link to the old historical question. There are detailed proce3dures and specs to set the static pressures and for the adjustments. Which ones have you done or attempted so far?

Expert:  Dan replied 1 year ago.

Meaning all the adjustments.... Which ones have been adjusted so far?

Expert:  Dan replied 1 year ago.

Do you have the manual with this information or do you need it to be able to test and make these adjustments?

Expert:  Dan replied 1 year ago.

Hi, Did you get this resolved?

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