Buying Advice Need to find a PT owner in Minnesota

[MossRoad]

I'm looking at my schematic right now.
The oil cooler is only used for the wheel motor circuit.
On the wheel motor circuit, the oil comes out of the vvp (variable volume pump) through the oil cooler manifold body, through the cooler and back to a return port on the tank.

However, the oil cooler manifold body is an unknown device. According to the schematic, it has no function. I would have to look under the hood to see if it exists.

The oil cooler manifold body is just an in and out block with a port for the temperature sensor that turns the cooling fan off and on.

 

[MossRoad]

The "hydraulic diagram" that came with my PT is nothing more than a hose routing schematic. There is no indication of flow direction, valve functions, etc. Don't expect too much.

There's not too much to guess on. If the hose comes out of a suction port on the tank you can follow it to a pump and determine direction from just that. It ends in the return ports on the tank.

The wheel motor circuits has oil in from the tank, and out to the cooler, then back to the tank. The wheels can turn in either direction, so the flow in those hoses is bidirectional. Same for the steering circuit.

 

[Clumber]

I'm looking at my schematic right now.
The oil cooler is only used for the wheel motor circuit.
On the wheel motor circuit, the oil comes out of the vvp (variable volume pump) through the oil cooler manifold body, through the cooler and back to a return port on the tank.

However, the oil cooler manifold body is an unknown device. According to the schematic, it has no function. I would have to look under the hood to see if it exists.

In the parts manual for my recent PT 425, the cooler is on the Steering Circuit, and not on the Tram (wheel motor) circuit. I scanned all the circuit diagrams, see photos. Note, the date indicates 2009, so they also may be out of date.

 

[J_J]

Pt-1445

The wheel motor circuit in my PT is a closed loop system. This means that a lot of the same oil is recirculated over and over, with the charge pump making up for any loses through the VSP, or wheel motors. The charge pump, pumps about 10 % of the total VSP volume. My wheel motors have case drains which collect at a manifold which includes a hose from the VSP pump casing. This fluid is then sent to the radiator, and then to tank. The charge pump fluid is drawn from the tank through a 10 micron suction filter, and maintains the volume of fluid for the closed loop circuit, and helps cool the VSP pump.

A lot of people whine about a suction filter, but Power-Trac must have got it right, because all the PT's have this setup, and has been in operation from the late 80's.

 

[J_J]

Clumber,

Do you have case drains on your wheel motors? Does your VSP/tram pump have a case drain?

You might call Terry at PT to verify just what the radiator is cooling. We know about the inaccuracies with the PT schematics.

Perhaps they did change the way the fluid is cooled. Cooling the PTO/steering fluid might be more efficient than the using the charge pump volume.

 

[Clumber]

Clumber,

Do you have case drains on your wheel motors? Does your VSP/tram pump have a case drain?

You might call Terry at PT to verify just what the radiator is cooling. We know about the inaccuracies with the PT schematics.

JJ, I'm not sure what a case drain is. Just beginning to understand the PT and the hydraulics. If you tell me what to look for on the machine I will take a look on the machine-- maybe take some photos. Its the only way to really tell for any particular machine.

 

[MossRoad]

In the parts manual for my recent PT 425, the cooler is on the Steering Circuit, and not on the Tram (wheel motor) circuit. I scanned all the circuit diagrams, see photos. Note, the date indicates 2009, so they also may be out of date.

Very interesting. That is completely different from my schematic. I went outside last night and verified that my cooler inlet comes from a large hose on the bottom of my VVP and the outlet of the cooler goes back to the tank.

I wonder why they changed it?

 

[Badback]

Can anyone think of a reason why a cooler could not be connected into the PTO return line? I'm thinking that the PTO oil temperature has got to be higher than the drive motor oil when using a load like a snowblower. Looks like a snowblower would be consuming nearly half of the engine HP.

I notice that there is a horizontal tunnel between the operators feet/legs. Does this conver have to be routinely removed for maintenance?

Anyone have any experience with extending zerk fittings with tubing to more convenient locations?

Just where are all of the screws that have to be removed for greasing?

Thanks.

 

[MossRoad]

Very interesting. That is completely different from my schematic. I went outside last night and verified that my cooler inlet comes from a large hose on the bottom of my VVP and the outlet of the cooler goes back to the tank.

I wonder why they changed it?

I'll bet they changed it when they switched from the hydroback cable to a hydraulic circuit to control direction. That probably used a different variable volume pump. Or, perhaps, the steering circuit has a more continuous flow of fluid from the tank? Just wondering. Or wandering. :laughing:

 

[MossRoad]

Can anyone think of a reason why a cooler could not be connected into the PTO return line? I'm thinking that the PTO oil temperature has got to be higher than the drive motor oil when using a load like a snowblower. Looks like a snowblower would be consuming nearly half of the engine HP.

I notice that there is a horizontal tunnel between the operators feet/legs. Does this conver have to be routinely removed for maintenance?

Anyone have any experience with extending zerk fittings with tubing to more convenient locations?

Just where are all of the screws that have to be removed for greasing?

Thanks.

My guess is too much flow in the PTO circuit for the cooler to handle. Don't forget... the main hydraulic tank also acts like a cooler.

The tunnel between the operators legs contains several things:

- The top link for the articulation of the two halves of the machine.
- The path for the hydraulic hoses and wiring.
- The treadle pedal and directional control valve (or hydroback cable on older models).

There are two side panels on the tunnel on my PT425. There are 3 bolts in each. They have to be removed to get to the lube points on my treadle pedal (with cable operated directional control) and the front top link.