3-Point Hitch TC40D 3-Point Bounce

Spicer · Apr 27, 2012

I thought I would share some of my repair findings.

3-Point Bounce problems can be diagnosed by lifting a 3-point implement and closing the flow control valve at the base of the seat. If the 3-point drops either the piston seals or relief valve is leaking. The hydraulic relief port is not shown on the hydraulic schematic that Jinman previously posted. It is unlikely that the relief valve is the culprit and the cylinder head must be removed to inspect the valve.

It is more likely that the piston seals are leaking. The piston seal consists of an o-ring and a Teflon backup washer. This is not as robust as a conventional hydraulic cylinder piston seal and is prone to failure.

Some repair findings. On this Tc40d I didn't have to remove the platform. The PTO engagement valve will not permit the removal of the head and cylinder as an assembly. Do not remove the PTO valve. When the head is removed from the cylinder as described below, these components can be removed.

Great care should be taken not to drop any contaminates or foreign objects in the case. It may not be possible to remove these objects without complete disassembly. Hydraulic repairs require cleanliness.

3-point cylinder head, cylinder and piston removal
1. Remove the seat and disconnect electrical connection.
2. Clean surrounding area with a pressure washer.
3. Remove flow control shaft and cylinder head fasteners.
4. Pull cylinder and head assembly forward.
5. Wrap a Vise Grip chain wrench around the cylinder as close to the head as possible. The chain wrench handle should be on the left side of the tractor with the chain hook facing up. Be careful not to entangle harness electrical.
6. Insert two 3/8 drive extensions into the holes of the head. Rotate the head to break the o-ring seal with a pry bar on the two extensions.
7. Remove the cylinder head by prying against the chain wrench chain and head 180deg apart on the head. The head protrudes 1" into the cylinder bore and will window cock.
8. Remove cylinder and piston. If the piston remains in the case, tie a string around the o-ring grove to assist in its removal.

Inspection
1. Replace piston and/or cylinder if scored or worn. The bore is 80mm
2. Stone or fine file any nicks on piston.
3. Break the glazing on the cylinder with a cylinder hone.
4. Apply air pressure to the relief valve port on the head. If any air exhausts though the tank port (opposite to the pressure port) the pressure relief valve will need to be serviced.
5. Replace all seals and gaskets.

jinman · Apr 28, 2012

Good for you, Spicer. Your post is full of great info. I didn't think it was possible to do the lift cylinder R&R without lifting the operator platform, but you certainly seem to have found the key to doing it. Did this fix your 3PH hiccup? Hope so.:thumbsup:

Spicer · Apr 28, 2012

Thanks for your input Jinman. Most of this was plagiarized from your previous posts.

I’m waiting for parts but the problem was obvious. When I remove the head and cylinder; the piston remained in the gear case. The seals were worn to the point that there was no sliding resistance with the cylinder. Even though the seals were heavily worn the cylinder’s honing pattern was still visible though out.

My initial concern was that these seals could break down and get trapped in the hydraulic system. This was not the case everything was intact.

Mike

RDrancher · Apr 28, 2012

Wow, thank you Spicer. You've given me new hope in fixing mine. Removing the platform was keeping this repair on the back burner.

Spicer · May 4, 2012

My 3-point repairs went smoothly and no more 3-point hiccup.

The parts totaled $38.00.

I didn’t mention above that the single stud that attaches the head to the gear box is a hindrance to the removal of the head with the chain wrench. The stud is a 12mm x 1.25 by 12mm x 1.75 and has low strength threadlocker on it. It may be possible to replace it with a 12mm x 1.75 bolt.

It’s possible to do the repair with the stud in place but it’s not possible to do it without using expletives.

Do not allow contaminates in to the hydraulic system.

Assembly
1. Clean all parts and sealing surfaces.
2. Oil all of the o-rings.
3. Install the piston o-ring. The o-ring is installed on the top or pressure side and the Teflon washer is on the connecting rod side.
4. Install the Teflon backup washer and make sure the beveled ends match.
5. Heavily oil all parts.
6. Install the piston from the top side (large chamfer) of the cylinder with an arbor press. The press will require an 11” opening.
7. Prop up the 3-point lifting arms so that the connecting rod doesn’t interfere with the cylinder insertion.
8. Install the cylinder and piston into the gear case.
9. Install the gasket and o-rings onto the head. If you use a small amount of “tack and seal” to hold the gasket in place, don’t put it near to the ports on the head. The sealant is a contaminate in the hydraulic system. The gasket must not interfere with the pressure port o-ring.
10. Loosely install the head onto the cylinder.
11. Install the fasteners and tighten them evenly to draw the o-ring into the cylinder.
12. Torque the head bolts down in an alternating sequence.
13. Start the tractor, open the flow control valve and fully cycle the 3-point up and down 5 times without a load. This will remove any trapped air.
14. Install an implement and cycle 5 times while checking for leaks.

The platform on this tractor was never an issue in removing or installing the cylinder, there was more than an inch of clearance. The only time consuming part of this project was removing the head from the cylinder.

I’m not an expert; I’m simply describing my repairs.

Mike

jinman · May 4, 2012

Spicer, are you aware that on later models of the TC45DA they did away with the port opening below the seat? Can you believe it?

When somebody in this forum told me that, I could hardly believe it.

Spicer · May 4, 2012

While poking around on the CNH parts search I noticed that boomers with factory cabs do not have the opening. I would have to think long and hard about cutting an access hole vs. removing the platform, cab, AC, heater, electrical and the fitting and adjusting that a cab requires.

Mike