# New Holland TC40DA Rear Differential Lock



## promax (Feb 2, 2016)

I just purchased a 2004 New Holland TC40DA from my Brother. 

The rear differential lock wont engage. The pin that pulls out of the rear gear housing when foot pedal is pushed appears to be frozen. I tried prying on it with a crow bar but didn't want to put to much force on it. 

My Brother purchased this tractor new and he didn't know it had this feature and never used it. 

Any advice?


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## HarveyW (Sep 15, 2014)

Welcome to the tractor forum, promax.

Your differential lock mechanism is probably rusted in place due to a lack of use. I have attached a parts diagram of your diff lock system, if it will help at all. 

Make sure the rear differential fluid level is full. Take the tractor on a high speed run (weekly basis) to throw oil all over internally inside the rear end. Try prying lightly on it before & after each run. 

I had 4th gear in my transmission stuck in neutral position due to lack of use. I pulled the transmission cover and pried on the shift fork and oiled the rail. No immediate improvement, but about a month later the 4th gear started working ok. 

If you are planning to tear into the tractor to repair the diff lock, you really need a service manual. Check ebay. I would try the oiling and prying method for a while.....

In the meantime, if you get stuck, brake the slipping/spinning wheel to make the other wheel pull. Works ok. That's how it was done before diff lock came around.


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## promax (Feb 2, 2016)

Thanks for the reply. I plan to remove the tire this to allow a closer inspecting of where the diff lock shaft goes into the gear housing. Then try to finesse it loose..


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