[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

(ET) Hot shunt



While looking for a service bulletin on hardened spindle replacement I remembered reading on the ET.org site, I came across a bulletin (#OPSB74-1), and thought of you E20 guys with hot shunts and stuttering relays.  The bulletin is actually included in the Manuals section, under the GE Service Manuals/Models E12/E12M + Service Bulletins.pdf.  I thought I'd retype it here for convenience, but if you want the figure #2, you're gonna need to go to that site.
 
"It has been reported that some E20 tractors have developed overheated current sensing shunt plates (lower control panel).  Indications are "chattering" of the FW relay or loss of the top three throttle speeds in the forward direction.  In severely heated cases, the drive motor won't start in forward or reverse even though the controls can be heard to pick up in normal fashion.  An examination of the shunt plate should be made for evidence of overheating.  If "warping" or discoloration is evident, then replace the shunt.
 
A new shunt kit is available, as shown in Figure 2. Use part number 247A7693G2 when ordering.  This new kit assures a tighter, more reliable connection by using different lock washers and eliminating the use of the insulator threads for electrical connections.  See Figure 2.
 
Loose connections at time of assembly or loosening from vibration at the threaded phenolic spacers will generate heat when current flows through the shunt.  For this reason it is imperaitve that, when replacing the shunt plate, the wires at the shunt be examined and wire terminals replaced if overheated."
 
Obviously, the kit's no longer available, but a measured wire can replace the shunt, although I don't understand how they got around using the insulator threads for connections.  Anyway, FWIW, hope this helps....
 
Tom