TEA20 Hydraulic Pump - identification question

[Peter in Queenstown NZ]

I have just split the transmission on my 1950 TEA 20 at the rear to replace a selector fork. Thats going well but am wondering what a small square key is doing lying on the floor of the rear section at the split. It is attached (loosely) through a hole in the hydraulic pump underneath the spline that drives the pump. I am a new member so don't seem to be able to attach a photo unfortunately. Any help appreciated
 

[Charles in Aus.]

Peter it sounds like the oscillating drive shaft , it is supposed to rock the control valve gently to minimise the possibility of seizing . It is held in by a circlip that often fails .
 

[Charles in Aus.]

A picture from the engineer's web site

 

[John(UK)]

It is the Oscillator for the Control Valve. Not all tractors have this and it will work without it although. The "hole" under the PTO shaft is the Control Valve, treat it with respect.
There is a small circlip that holds it all together in the open end of the Control Valve, make sure that this clip locates properly or it will come apart again. Avoid touching the Control Valve polished outer surface as this will easily get marked and this could cause the Valve to stick. Never park the tractor with an implement in the raised position and with the Pump not running, as that can also cause the Control Valve to stick. There is no need to leave the implement in the raised position and it is dangerous too. I have attached a drawing of the Oscillator and Control Valve. There is a later type as well that is made of flat strip, but it does the same thing. If you have any problems with this, email me...John(UK)....fergusontractors@hotmail.com

 

[Joe TO Fan]

John(UK): Not to try and derail this topic, but on my TO30, I always lower my blade down on an old stump, about a foot high, before I shut off the tractor. Should I avoid this and lower it all the way?

The main reason that I do that is with the snow, melting and refreezing, it is sometimes frozen to the ground, quite solidly.

Thanks in Advance

Joe
 

[John(UK)]

Joe, The idea of lowering the implement is to remove any pressure in the system so that it doesn't lock the Control Valve. Lowering the implement down onto a tree stump is just fine, you have no pressure in the system when you do this...John(UK)