Hydraulic HELP!!!

[ShawnAgne]

I rebuilt the pump installed it and all was well. However when I was running the cylinder I added through the bypass block it made a noise and started hearing a clicking. Shut the tractor off. The nut on the backside of the pump gear was coming loose. So Tightened that down extra tight. Checked by manually running oil through and it was still moving oil. Installed it with the bypass block still on, nothing. Took the by-pass block off and have it in stock hydraulic configuration and it still doesn't work. I've added the fluid (Hy-Trans) like I always have but can't get the arm to move. What did I do wrong? What is wrong? Please help.

Thanks in advance.
Shawn

PS- Was reading some other threads on similar issue. Since I can manually turn the pump and oil will move from one side to the other I assume the washer is not in backwards. Does this just sound like an air issue where I need to just cycle the lever a lot and let it run?

[Glen]

Hi,
The pump should have a washer at the drive gear nut that you bend over one of the flat places of the nut to lock it on. This keeps the nut from coming loose.
Here is a listing for it at TM Tractor.
It might have gotten air trapped in the tubes, some of the guys on here say it does happen.
I think he said loosen the 2 bolts holding the tubes to the pump, and let fluid run through the tubes, then tighten the bolts again.

http://www.tmtractor.com/new/hy/562fp.htm

[Don McCombs]

If your lock washer is missing and you don't want to spend over 40 dollars on a replacement, use a 3/8" inside toothed lock washer and some green (after-assembly) threadlocker.

[ShawnAgne]

Yes that was the initial problem I didn't bend the lip of the lock washer back up. Now it is bent up. I will leak some oil out of the pump end and then give it a try.

[Jim Becker]

You also need to make sure you didn't shear the key that goes between the gear and the shaft.

Once you get past this problem, you need to figure out the root cause of the problem so it doesn't happen again. Since you were doing something with a bypass block and remote cylinder, you may have dead headed the system. Doing that can cause a lot of damage.

A short explanation: Whenever a hydraulic pump is running, hydraulic fluid is flowing from the outlet through some path back to the reservoir. When the control valves are all in neutral, the flow may go through the valves and return directly. Fluid will be under low pressure. When a valve is actuated, the flow will go into a cylinder or whatever while fluid in the other side of the cylinder returns to the reservoir. Pressure in the system will depend on how much load is on the cylinder, increasing to whatever is required to lift the load. If the piston in the cylinder reaches the end of possible travel, motion will (obviously) stop. Pressure in the system will increase in response to the now arbitrarily large load. Since the fluid can't compress, something else has to give before the pressure hits infinity. The system is designed to deal with this event by including a pressure relief valve. When the fluid pressure reaches a predefined limit (1,100 to 1,500 psi in a Cub), it will push a valve open that dumps the fluid back into the reservoir. If there was no relief valve, the fluid would have nowhere to go, which is referred to as "deadheading" or "deadending" the system. If this is allowed, your best case would be for the engine to immediately stall. Other outcomes are to have the fluid blow out of the weakest point in the system, such as a hose, solid tube, gasket or oil seal. Or, the mechanical gear drive that turns the pump could break.

The Cub hydraulic system has a built in pressure relief valve inside the main Touch-Control unit. When you put in a bypass block, you are diverting the fluid flow before it reaches the pressure relief valve. So another pressure relief needs to be in the added circuit before the flow reaches any other components. Some added control valves have a built-in relief but you need to make sure it is not preset way above the Cub operating pressure. A valve set to high, is about like not having one! Valves with a pressure relief normally have an additional line that can return to the reservoir filler plug.

[ShawnAgne]

Yeah I had a blow in the hydraulic pump previously why I had to rebuild it. Why I reinstalled the pump and it was working until the nut came loose. So I have the pressures all back to normal and I've removed the bypass block and additional valve.