NH L555 Hydrastatic no drive Rside

[jaj]

Help would be appreciatted. I have L555 with very low charge pressue 50 psi( sould be 175) and no drive on right hand side. In fact at times it seems to lock up. I drained oil and inspected RH chain case and all is fine, removed RS hydra pump and all is good there too. Any ideas???

 

[Mike10]

Two possible causes, defective check valve back by the oil filters or internal damage. The check valve is what produces the charge pressure
You said you removed the RS Hydro pump, the hydro pumps are mounted to the engine bell housing. Did you remove this pump or did you remove the hydro motor that is bolted to the side of the chain case. If you are having low charge pressure without stroking the hydro levers, then I would look at the pumps. If the pressure drops when you stroke the levers then I would look at the hydro motor.

 

[jaj]

Two possible causes, defective check valve back by the oil filters or internal damage. The check valve is what produces the charge pressure
You said you removed the RS Hydro pump, the hydro pumps are mounted to the engine bell housing. Did you remove this pump or did you remove the hydro motor that is bolted to the side of the chain case. If you are having low charge pressure without stroking the hydro levers, then I would look at the pumps. If the pressure drops when you stroke the levers then I would look at the hydro motor.

I did remove the check valve and take a look all seems to be ok, no broken springs and poppet looks fine, As stated I removed the RS hydrastatic Pump and it all looks really good. I cannot say of the charge psi falls further when the levers are stroked but the charge light is on all the time. If I remve the motor what will I look for specifically? also any idea why it may lock up what appears to be mechanicaly on the RS side. This unit always worked fine until the other day. basically turned around and then had no RH drive!! Would a worn gear pump be a potential cause? The lift circuit operates ok but just wonrdering what else might be causing the low charge psi?

 

[Mike10]

I did remove the check valve and take a look all seems to be ok, no broken springs and poppet looks fine, As stated I removed the RS hydrastatic Pump and it all looks really good. I cannot say of the charge psi falls further when the levers are stroked but the charge light is on all the time. If I remve the motor what will I look for specifically? also any idea why it may lock up what appears to be mechanicaly on the RS side. This unit always worked fine until the other day. basically turned around and then had no RH drive!! Would a worn gear pump be a potential cause? The lift circuit operates ok but just wonrdering what else might be causing the low charge psi?

Since the pump looks ok I would start with the check valve. Remove the charge pressure hose from the top of the hydro pumps and plug. Have the thottle lever in the off position so the engine will not start. Crank the engine and see if it builds pressure in the charge line and gets close to the 150.
There is a forward and reverse relief valve in each pump body. Unlikely that both relief valves would fail at the same time. You can reach two of the relief valves from the top. One for the right side and one for the left side. You can remove these two and switch them and see if the right side will move either forward or backward.
If you have a bad internal leak you will have a lot of oil going out the case drain line. The case drain lines come out the side of the pumps and goes to the left chain case. Remove the lines and install hoses with one end in a bucket. Start the engine and see how much oil is being drained from the cases. If you have a big stream you have an internal leak. There is always some oil leaking internally but should be a small stream.
I would not worry about the motors at this point. They only get oil when the levers are stroked. You may hear noise coming from the motor because the motors are not getting a good supply of oil and the pistons are slapping against the swasch plate.
A week hyd pump would be noticable in the lift and bucket circuits. If the engine pulls down when the bucket or lift is dead headed then the pump should be good enough to operate the hydro.
Does the engine pull down any when operating the right control lever?

 

[jaj]

Since the pump looks ok I would start with the check valve. Remove the charge pressure hose from the top of the hydro pumps and plug. Have the thottle lever in the off position so the engine will not start. Crank the engine and see if it builds pressure in the charge line and gets close to the 150.
There is a forward and reverse relief valve in each pump body. Unlikely that both relief valves would fail at the same time. You can reach two of the relief valves from the top. One for the right side and one for the left side. You can remove these two and switch them and see if the right side will move either forward or backward.
If you have a bad internal leak you will have a lot of oil going out the case drain line. The case drain lines come out the side of the pumps and goes to the left chain case. Remove the lines and install hoses with one end in a bucket. Start the engine and see how much oil is being drained from the cases. If you have a big stream you have an internal leak. There is always some oil leaking internally but should be a small stream.
I would not worry about the motors at this point. They only get oil when the levers are stroked. You may hear noise coming from the motor because the motors are not getting a good supply of oil and the pistons are slapping against the swasch plate.
A week hyd pump would be noticable in the lift and bucket circuits. If the engine pulls down when the bucket or lift is dead headed then the pump should be good enough to operate the hydro.
Does the engine pull down any when operating the right control lever?

Thx for your assistance. it will be a few days before I get back to it however I will advise when I do with results. once again thx for your help