PT-422 and 425 Tram Pump I.D.

[Anonymous Poster]

I was at Power Trac on Thursday picking up some additional attachments (the mini-hoe, large bucket, and forks) for my 422. Although I recognize they don't give manufacturer information out on parts such as the tram pump and wheel motors, I thought I'd ask anyway. I was specifically looking for specs on the tram pump system including displacement, maximum rated pressure, and relief settings. They said they could not provide that information but did identify that the manufacturer of the 400 series pump was Sunstrand. A quick internet search after I returned and I found what I am very confident is the pump used in the 422 and 425. It is the 15 Series variable displacement pump described in the this document-Variable Pump Info. The installation drawings included on page 25 matches the pump in my unit. One thing that I believe the drawing shows is that the tram system does not have relief valves installed. This explains why using rated values for the wheel motors you should only be able to climb hills up to about 20 degrees, but yet many people on this forum have identified being able to climb steeper slopes than that. I think this is because the designers just allow the motors to be over pressured temporarily on steep hills or when pushing a heavy load.

 

[johara1]

PatH,
i have a 422 also,the power of this unit is good,and i did travel up and down and sideways on a 2 to 1 slope to see the limits of this one.
the only limit is the problems with the engine and or lack of support. it's down now for the governor(came apart inside the engine) otherwise it's great.
the true test is the mower and the hills here.
i looked at a number of wheel motors if i change anything thats where i will start. i found ones in the 7000 inch lb. range with a internal brake made by parker for $300 each. /forums/images/graemlins/laugh.gif

 

[Anonymous Poster]

I stand corrected on my previous statement about the tram pump not having relief valves. There are two large hex heads on the back of the pump that appear to be the relief valve cartridges. Now, if I just knew what they were set at.

 

[bryce]

Do they make one without the internal brake that has the same specs? I would like to upgrade if I can find the right parts. Robert /forums/images/graemlins/cool.gif

 

[Schultz]

Hopefully PT has choosen to keep the releif pressures below the specified continous operating pressures in order to provide a longer than 1000hr pump life. I imagine the pump is well below the max continous pressure most of the time anyway.

Continuous Maximum
Product Pressure Pressure
Series 70-BD 1000 2100
(69) (145)
15 Series 2500 4500
(175) (310)
Operation at these pressure limits (under normal
conditions) will give a five year life expectancy (@ 200
hours usage per year), assuming recommended
maintenance procedures are followed. In the event
that an extreme duty cycle is anticipated, consult
Sauer-Sundstrand.

 

[Anonymous Poster]

Robert,
I'm not sure what units Johara1 was looking at but Parker does have a series of small frame motors that look like they would directly replace the ones used in the 422 and previous 425s. The TE series shown at Parker Wheel Motors look like they would be a direct drop in for the White motors used by PT. They offer units that would provide up to about 88% more torque than the White units installed from the factory if you are willing to give up the top end speed. The other thing I like about these is that they have a somewhat higher bearing side load rating than the White motors. I may do the change out some day. I don't like the fact that with the existing wheel motors the pushing force is limited by the motor torque instead of the tractor's traction. I'd go with the TE0260 which I priced at $249.00 each.

 

[johara1]

PatH,
i was looking at the tg series,maybe over kill?
i was planing to fabricate a mount like pt used on the new 425. the 71/2 x 71/2 x 10 size was not a factor.