Power-trac hydraulic questions

[davesisk]

Who can (and is willing) to describe a little about the hydraulic layouts in the Power-tracs? (I'm particularly interested in my older 1418 of course, if anyone has any knowledge...<g>) I'm hoping this thread will be educational for everyone, not just me!

In mine, there's apparently a gear-type pump on the front of the engine that's fed by the tank with filter in between. I gather than the wheel motors are driving by this pump, as well as a supply to a 2nd pump. There's a right/left throttle operated switch on pump #1 that (I'd guess) sends oil in the right direction to splitters for the wheel motors, then a line that goes to the presumably piston-type pump #2 mounted on the back of the engine. Pump #2 (according to Don at Power-trac) powers the steering cylinders, lift arms, and external hydraulic ports.

So, questions (somewhere between theory and practice, I guess).

1) Does anyone happen to have a layout that shows which lines run where?

2) Why is getting air into the lines such a bad thing? How does it damage the gear-type pumps, for instance? Will it also damage the piston-type pump? If so, why isn't it necessary to bleed lines feeding fluid out of the gear-type pump and into the piston-type pump? I'm assuming the gear-type pump feeds the piston-type pump since there's only one filter. Is this a correct assumption?

3) Why gear-type to drive the wheels, and piston-type to power cylinders? Are gears alway matched with hydraulic motors, and pistons always matched with cylinders? (I'm assuming that the front pump is indeed gear-type and the rear-pump is piston-type. They're certainly shaped differently...)

4) Are there any good books that talk about the types of hydraulic systems you find in these tractors?

Best regards!
Dave

 

[MossRoad]

Here goes my best shot/w3tcompact/icons/smile.gif

1. Yes I have a layout. No, you can't have it/w3tcompact/icons/tongue.gif. This is because it is probably copyrighted by Power Trac and I don't want to get in trouble. However, I CAN tell you that the book has a great hydraulic diagram in it. You should be able to purchase one from Power Trac. Order it with some filters.

2. From what I gather air starves the pump of lubrication. That's all I know on that one.

3. The wheel pump is a variable volume pump. I don't think you can get that with a piston pump. <A target="_blank" HREF=http://www.tractorbynet.com/cgi-bin/compact/showflat.pl?Cat=&Board=genoperating&Number=99598&page=&view=&sb=&o=&vc=1> Click here to read a thread on HST and variable volume pumps</A>

4. <A target="_blank" HREF=http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/5-499/toc.htm>Click here for some good readin' on hydraulics for a starter </A>

 

[davesisk]

Actually, I've ordered the manual for the 1418 from PT, but Don told me that it doesn't have a diagram of the hydrualics (since this machine is about 12 years old). Sure you don't have a JPG of that hydraulic diagram??? [G]

 

[MossRoad]

I'm surprised that it is not the same as the PT400 series. I don't have it digitized, it is in the manual. Did they say it is different from the PT400 series?

 

[davesisk]

Yup, Don said it's totally different from the new 400 series. However, what I was thinking was that if I could see how it works and is routed in a newer machine, then perhaps I could more easily figure this older machine.

I suppose I could just also order a manual for the 422, eh?

Regards,
Dave

 

[MossRoad]

Well, sorry then. I guess I should have said that I have one for the 400 series. I didn't realize they made changes, although it doesn't surprise me. I'll look around some more and see what I can find /w3tcompact/icons/wink.gif.