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Caterpillar/Towmotor V50B Key Switch Schematic?

Birken Vogt ยท 2018-02-15 23:47

Might need to replace key switch on this one. Serial 81M4397 Looking to learn what the various terminals on the key switch are for. There are more than power, ignition, and starter but I can't tell what they are for.

Replies9
  1. #1Cmark2018-02-16 01:42

    Cat forklifts aren't on SIS and information is hard to come by (from my perspective anyway). Maybe a photo will help?

  2. #2kshansen2018-02-16 08:45

    Any chance there is a Cat Part Number on the switch? Just on the chance Cat used the same switch on something else. It may be a long shot but got to go with what you have. Are there any letters next to the terminals, some times they are easy to figure out that way. And yes pictures are always nice!

  3. #3wornout wrench2018-02-16 16:32

    Birken I borrowed a service manual off of a friend. It covers V30C-V50C His is an older machine, not sure what the serial number range is of the book. Is this even close?

  4. #4Birken Vogt2018-02-16 16:50

    Thanks for the help. I got the immediate problem solved (lost the key in the yard/thought I was going to have to replace switch with one I had laying around/found the key) I believe the V50C is very similar, I have seen a few and they look the same. Since I have a schematic now, maybe you guys can help me figure out why it will start then die several times when cold. Just like the ignition was cut off. Does not matter if you rev it up or just let it idle. It will run a few seconds and stop. Restarts fine immediately. Up to 3-4 cycles of this when cold. Never when warm. Fuel is propane on this unit.

  5. #5wornout wrench2018-02-16 18:52

    There are a few more schematics in the book, might be one for the propane part. I will have a look when I get back home

  6. #6G Doyle2018-02-20 22:27

    caterpillar key switch part # 366463 or TVH part# sy45796 any local forklift dealer or independant should have that in stock , very common part for cat hyster clark etc. Check for voltage drop from oil pressure switch to propane lockoff, very common (should be continental F145 engine) for low oil pressure to switches when cold. 81M is the last of the B series. the C series wiring is very close to the same.

  7. #7Birken Vogt2018-02-20 23:29

    I have been studying the schematic in post #4 but I don't see the propane lockoff switch/coil. Is it there, or is the drawing for gasoline only? It sure seems like a lockoff problem, if I had to guess.

  8. #8G Doyle2018-02-22 09:00

    CAT V/T50B wiring diagrams dependent on ignition system. Part number for oil pressure switch is #024759. Doyle

  9. #9Birken Vogt2018-02-22 10:03

    G. Doyle, thanks for the pictures but they came out too small and blurry even if I blow them up.