Staghound Hydramatic Transmission Question

[rob love]

As I said in my last post, every job ends up with 3 more. It turns out that one of the switches was only loosely in the transmission while the other switch (the bent one) was in so tight I had to modify tools to get it out. It turns out neither switch was appropriate... the right one was a 60psi normally open, so the light would have come on at 60. The other one was 4 psi normally open, so the light would have come on at 4 psi. Both switches were two terminal, so required a new wire running from ground to one post of the switch. Both sides merely had the ground wire end taped to the wiring conduit, which is by no means a suitable or dependable ground.

Going by the Honeywell chart for Hobbs switches, a suitable switch would be a Hobbs 78154 (60 psi) which is a single terminal normally closed. An alternate will be Hobbs 76064 (60 psi) normally closed 2 terminal, which would require a ground wire to be provided. In the case of your lower pressure transmission Malcolm, these switches can be adjusted, so you could lower the pressure to 54 and get rid of the annoying warning light as well as prevent accidental application of the starter. Here is a link to the Hobbs chart on the switches: https://sensing.honeywell.com/index.php?ci_id=49633 Watch out as there are variations to the pressures within each part number given, which will be reflected in two extra digits after the part number. They are easy enough to adjust however by removing the little rubber plug at the top and turning the screw in or out as required.

I noticed that the two transmissions in the tank are slightly different. One has only 1 port in between the two adjustment screws on top, while the other has that port as well as another forward of the adjustment screws. I'll have to investigate if the pressures are the same in both ports, or if I should be using the same port location on both transmissions. Currently the last people used the one center port and one forward port.

I tried doing some of this work from underneath, but it is near impossible. So I am now laying in the turret basket, having removed the appropriate ammunition bin and floor plates. There is no comfortable way for a 240 pound man to be laying in the bottom of the turret basket.