Testing Bennett shifter....

[Iver]

I have a used Bennett shifter for my Allison 5 spd. Before I install it I wanted to bench test it first.
The guy I got it from said he rode in the coach where it was previously installed and it worked fine.
He also said it is 12 volt.

So I hooked it up to air. (around 65-70 lbs)
Set up a 12v battery and grounded the shifter
When I tried putting 12v+ to either solenoid, I got no response.  No clicking, no air, no movement.

There are no markings on the shifter or the up/down solenoids.  The solenoids each have 2 wires.  One ground and one power.
I can move the shaft easily by hand and the contacts for the gear indicators work for each gear.

With air and power, it should do something???  How do I tell if it is 12v or 24v?
     Thanks,   Iver. 

[luvrbus]

Check on the housing if you have a numbers like AS750-01 (V) it will be 24 volts no (V) for the 12 volt.
I am at a lost here about the 2 wires inside the cover you have 5 skinner valves and a valve on each end for up shift( located where the air supply enters) and downshift if it is electric/air the wiring leaves the shifter pad and goes through the relays leaves there with a 16 wire harness the part that mounts on the transmission should have a 16 pin plug about 18 inches long make sure you have the ground cable from the unit to the rod very important to make shift

good luck

[Iver]

This is what it looks like....
  Thanks,  Iver

[img][img]

[Iver]

All I could find is a small #5 on the end of one of the up/down solenoids.

There might be a tag or numbers under the unit but I would have to remove it from the mounting bracket
which would mean removing the copper air line and fittings which connect the 2 solenoids behind the bracket.
I would rather not disturb those fittings unless I had to.

Any other way of testing 24v or 12v?
        Thanks, Iver.

[luvrbus]

Do you have the harness from the unit each one of the nuts are skinner valves that open with power when the shifter tells it up or down they need power to each from the shifter pad to work, so power the upshift and have air, supply power to one of the skinners ( neutral is the last one by the upshift) the shift rod should go out

good luck

[Iver]

I talked to the guys at United Transmission Exchange in California.
Everyone there were very helpful.  I spoke with Bob, Steve, and Donny who does the Stone Bennett stuff.
He went out of his way to test several 12v relay solenoids he had in stock with an ohmmeter and compared the
numbers with my testing of my relays.  It turns out the resistance was different.
  We both concluded my relays must be 24v.  So I tried 24v to activate them and everything worked.
I was told the relays were 12v from where I got the shifter but they don't have any markings on them at all.

Actually this will make wiring the shifter a little easier but I will have to revise my wiring diagrams.
         Thanks, Iver.