TN70A Hydraulics

[JASTN70D]

As a proud /forums/images/graemlins/grin.gif new owner of a TN70DA. It has come to my attention that a simple matter of accidentally putting a remote lever in to the use position with nothing hooked to the remote could cause a "dead head" situation. And in turn cause severe damage to the system.

I have owned in the past other tractors with rear remotes and have never experienced any problems . But frankly I do not remember if I ever accidentally left a lever actuated without an attachment .

I am looking for some guidance on this as it seems strange that you could so easily damage the hydraulics in this manner

 

[slowzuki]

Most tractors with remotes if you leave the remote in a detent position it will cause the pump to operate at relief pressure. It would be the same as continuing to operate a cylinder once it had reached the end of it's stroke.

 

[mahlers]

I was told that this wouldn't hurt anything - it would just pop the relief valve. You would have a hard time starting the tractor in this condition, though - but it would be pretty obvious what's going on. On mine, the remote lever is spring actuated so that you would physically have to hold it in the use position - is yours different?

I've run into a similar situation with my backhoe. When you remove the backhoe you need to install a jumper hose to the hydraulic fittings or the tractor bogs down really bad.

 

[DocHeb]

I have driven my TC40D around with an unused remote engaged. I didn't notice it until I tried to raise the three point and nothing happened. Took a few minutes to figure it out - and after I returned the remote lever to the neutral position, everything was back to normal. No damage that I can tell, and everything continues to work well. I've actually done this several times (he admitted sheepishly /forums/images/graemlins/blush.gif). However, this is just anecdotal. I would expect the relief valve for the auxillary pump to "pop" and prevent any damage, just as if you asked the remote circuit to do too much and had an effective "dead head".

Are you sure that your problems are true cause and effect?

 

[JASTN70D]

</font><font color="blue" class="small">( On mine, the remote lever is spring actuated so that you would physically have to hold it in the use position - is yours different? )</font>

Yes mine does have the detent on both remotes so they will stay were you put them.

I guess I should elaborate on this I had an unfortunate problem after 2 days use of the Tractor the Hydraulics failed. It turns out that the shaft to run the pump was installed wrong at the factory.

It is the dealer who suggested this when he first heard about the pump failure. He was sure I had left a remote on or tried to raise the 3 point with the "lift-o-matic" while the 3 Point BH was mounted.

I was more than a little perturbed that the first thing he did was blame the operator. You would think he would at least have waited until he set his eyes on it. In any case I know what a relief valve is for and certainly know what one sounds like when it is in bypass.

Now I am not sure if the dealer does not know better or was trying to get out of warranty work. He did say he has had to change out pumps in the past that got burned up by dead heading. I am just not sure how you could dead head with a pressure relief valve in place. I know if it is as easy as leaving a remote on I better stock up on some pumps.! /forums/images/graemlins/frown.gif /forums/images/graemlins/frown.gif

 

[DocHeb]

I had a similiar failure after owning my tractor for 24 minutes!. There should have been a snap ring on the shaft from the flywheel to the charge pump. My dealer said it was just missing. I didn't have time to mess-up the remotes within the first 24 minutes of ownership.

For further info:

11. Sudden failure of Transmission Hydraulic Pump, resulting in no HST motion and no PTO rotation, yet engine runs well.
TC40D HST/PTO Failure
TC40D PTO/Hydro Problem

 

[JASTN70D]

Chris

Sorry to hear that. I can relate not much fun waiting all that time for delivery and then watch the tractor go right back to the dealer.! /forums/images/graemlins/mad.gif /forums/images/graemlins/mad.gif /forums/images/graemlins/mad.gif

This is a replacement for a lemon of a different color. I had that Tractor 6 months and it went back to the dealer 4 times. It would have been much more had I not done most of the warranty work myself.

Oh well enough self pity for me. I just want to get the Tractor back and never see it go back to the dealer. Thats why I want to be sure I can not break the hydraulics that easy.

 

[RickB]

Forcing full hyd pump output over the system relief valve for an extended period will trash the pump on just about any open center system ever designed. How long it will take can vary, but the results are the same. Hydraulic detents on TN and TNA remote valves are pressure adjustable, and should be checked at pre-delivery. Cable drag and lever pivot drag can cause problems. When customers use a remote valve as a power beyond source, such as with a backhoe or log splitter, I insist on using a bungee or similar device to hold the lever rather than adjusting the detent release. This allows normal function when the valve is used to operate a simple cylinder, perhaps saving a pump failure.

 

[ZJ_HR]

Exactly my way of mind /forums/images/graemlins/smile.gif

 

[PineRidge]

RickB will the use of power beyond instead of the rear remotes to power the BH eliminate a problem failure such as this?