Wish we had a clutch....

[MossRoad]

As many/most PT owners in cold weather areas know, our three hydraulic pumps are directly connected to our engines, and cranking them over, both gas and diesel, in cold weather can be, um.... hard! :laughing:

We've been pondering why there's no clutch(es) to disconnect the pumps for easier starting of the engines?

Anyhow, I have no plans to do this, so it's just food for thought.

I am more familiar with the electric clutches on mowers that engage/disengage the belt pulley from the PTO shaft. These types of clutches would not work for our applications.

While going through one of my Kohler manuals, I came across a mechanical PTO clutch diagram. See screenshot.




Anyone familiar with these types of clutches, and if they are even made anymore? Are these just for belt driven implements, or could it power a shaft driven pump?

 

[BobRip]

I can certainly see the advantages of a clutch. The screen shot was not very readable on my phone. I will try the computer.

 

[Marks481]

While going through one of my Kohler manuals, I came across a mechanical PTO clutch diagram. See screenshot.

No problem. Just weld a 12" extension onto the engine compartment and you can shoehorn that baby right in.

Of course, since you have pumps on front and back of your engine...

 

[BobRip]

OK, the drawing looks good with my computer. You could do what I did and have an attached garage with R50 insulation in the wall and R55 in the attic. Never gets below 60 (well rarely).

 

[/pine]

Compression release maybe??

 

[MossRoad]

OK, the drawing looks good with my computer. You could do what I did and have an attached garage with R50 insulation in the wall and R55 in the attic. Never gets below 60 (well rarely).

Don't get me wrong, I can start the Kohler to -5. It's just a huge strain on the engine and battery, etc... I'm fairly certain it would just POP right off if it didn't have that load. And it might help a lot of the folks that had the starting issues with the Robin engines.

It's an interesting thing to discuss, that's for sure.

 

[MossRoad]

Compression release maybe??

The starter would still have to push over all three pumps and the cold hydraulic oil. But that might take quite a load off.

 

[MossRoad]

I can't find any compression release for a CH25.

 

[Tractor Tech]

So, I will say right up front I'm not familiar with the Power Trac, but wouldn't it be easier to figure out a bypass at the pumps so that you're not trying to move oil through the whole system? Just asking

 

[MossRoad]

So, I will say right up front I'm not familiar with the Power Trac, but wouldn't it be easier to figure out a bypass at the pumps so that you're not trying to move oil through the whole system? Just asking

Well, that's a good question.... I'll give it my best shot.

When the treadle pedal is not pushed, the swash plate in the tram pump is neutral, so no oil is being pumped outside of that pump through the wheel motors at that point. However, hydraulic oil is still constantly being pulled from the tank, through the filter and then through the charge pump on the tram pump, then back to the tank.

Then we have the two other pumps.

One is for the main PTO pump.
The main PTO is bypassed from pump to tank and back to pump until the PTO diverter switch is turned on to divert the fluid out the hoses on the FEL arms. So that circuit is already about as short as it can be with very little resistance in the plumbing.

The other pump is for steering/lift/quick attach/AUX PTO.
That one goes from the pump to the steering valve, through the power beyond port on the steering valve, then to the 3 spool valve bank on the FEL/AUX PTO circuit, then back to the tank. So there's some resistance to flow in that circuit. But it's open center, so the steering valve and 3 spool valve are just open pipes until the valves are manually activated by the operator.

So, I think all of the resistance that we're pushing against with the starter is already about as bypassed as we can get.

Even though everything is pretty much bypassed, when it's cold, it's still like stirring a cold honey pot.

Disengaging the pump shaft(s) with a clutch would be where we'd get the most bang for freeing up the engine with no load.

 

[cqaigy2]

Not to pick a nit, but is that true that the oil is flowing thru the filter when tram is in "neutral"?

 

[aczlan]

Not to pick a nit, but is that true that the oil is flowing thru the filter when tram is in "neutral"?

If it is a variable displacement pump (which I believe it is), there is no fluid flowing through it when it is in neutral.

Aaron Z

 

[groundcover]

Wonder if they could run all the pumps out the back and through something like this, works on my chipper and it’s 140hp !
Mechanical Power Takeoff - Mechanical PTO | Twin Disc

 

[MossRoad]

Not to pick a nit, but is that true that the oil is flowing thru the filter when tram is in "neutral"?

After you change the hydraulic filter, what's the next thing you're supposed to do?

Bleed the pump.

How do we bleed the pump?

We disconnect the spark plugs, stick the hose on the bleed port and the other end into the tank.

Then we crank the starter and watch the air bubbles.

Where are the air bubbles coming from?

Fluid being pushed through the pump.

The swash plate is in neutral.

Is my thinking incorrect? It has been many times before, so have at it if I'm mistaken.

 

[MossRoad]

If it is a variable displacement pump (which I believe it is), there is no fluid flowing through it when it is in neutral.

Aaron Z

I think the charge pump is constantly pumping.

 

[aczlan]

I think the charge pump is constantly pumping.

Most likely, but if the swashplate is in neutral the high pressure tram pump should not be pumping anything through beyond what the charge pump is pushing through.

Aaron Z

 

[MossRoad]

Wonder if they could run all the pumps out the back and through something like this, works on my chipper and it’s 140hp !
Mechanical Power Takeoff - Mechanical PTO | Twin Disc

My 2001 PT425 model year has pumps on both ends of the motor. I'm not sure which year, but several years after mine was made, they moved all the pumps to one end of the motor. So, yes, something like that would work very well, if it had all the correct bolt patterns, etc... and the tub might have to be lengthened to make it fit.

I'm not planning on making any changes to my machine. It's just a question I ponder every time I'm out there in sub-zero temps wondering if it's gonna start. It always starts. But I still wonder! :laughing:

 

[MossRoad]

Most likely, but if the swashplate is in neutral the high pressure tram pump should not be pumping anything through beyond what the charge pump is pushing through.

Aaron Z

If the swash plate is in neutral, no fluid is being pumped through the wheel circuits. The pump is still spinning, but the plate is in a neutral position. We agree on that much.

The charge pump is still pumping. It has no neutral position. It always pumps. I believe it's a fixed displacement pump. It can't be disengaged.

 

[MossRoad]

 

[zzvyb6]

Would a cold weather (low-vis) hydraulic oil make an improvement? or an oil heater ? or a higher CCA battery ?