Cat 287C parking brake engages on steep slope

[Jobiss]

I use my 287C to maintain my motocross track and it has a few steep slopes. Often, when I work on them, the parking brake goes on and I need to push the button several times while moving on the seat to get it off (I don't know if moving on the seat helps). Does someone knows what causes this and how to avoid it if possible?
Thanks!

 

[KSSS]

I have seen that issue when working on steep slopes that if your butt moves too much off the pressure switch that the brakes will come on. I would guess that is what is going on. Maybe try seat belting yourself in to hold yourself on the seat and see if it still prevents the issue.

 

[Jobiss]

Thanks. I always use the seat belt, and pretty tight. Maybe I'll try tighter. Can we bypass that pressure switch?

 

[Nige]

If the seat is getting tired the foam in the cushion can go somewhat hard. That in itself can prevent correct operation of the “operator present” switch - which is there for a reason.

 

[Nige]

Can we bypass that pressure switch?

I should have mentioned this before. Apart from for the purpose of a temporary "get you home" or a bypass for testing, nobody on HEF is going to help a poster to knowingly defeat an installed safety system.

 

[Jobiss]

Ok, I understand. But it’s really not cool to be stuck on a steep slope. If I can’t release the park brake I’ll be in troubles. Is there an easy way to avoid it just when I get to work on steep slopes, if you can tell me? I don’t think I’ll change the seat for that. I had a 2005 Cat 277B which I used for 3 years on the same slopes and never had this problem.
Thanks

 

[Nige]

You could try replacing the seat pressure switch.
Does your machine S/N start with MAS or SSB.? Trying to identify the correct Part Number for the switch.

 

[Jobiss]

MAS01517

 

[Nige]

Have a dig around the back side of the seat. Can you find a 4-wire harness with these wire numbers/colours on it.? Is it connected to anything.?

 

[Jobiss]

I’m not near the machine. As soon as I can I’ll look at it and get back to you. The air seat is not working anymore. It doesn’t bother me, but can it be in cause?

 

[Jobiss]

It must be a pretty big job to replace this switch!?

 

[Nige]

I’m not near the machine. As soon as I can I’ll look at it and get back to you. The air seat is not working anymore. It doesn’t bother me, but can it be in cause?

As the operator presence switch and the air compressor switch for the seat are both powered through the same harness I'd say take a close look at that connector and clean the connections for a start. You should have 12v if you measure between the 180 Green and the 200 Black wires when the key switch is on.

 

[Jobiss]

Yes I have this harness and it’s connected. After the connector, it splits in 2: one red and one black on each side

 

[Nige]

Yes I have this harness and it’s connected. After the connector, it splits in 2: one red and one black on each side

Look at the wires coming into the connector. There should be two greens, a black, and a purple.
If you look at the back side of the incoming half of the connector with the sockets in it, the pin positions will be marked 1 thru 4.
Identify Pins 1 & 2. That should correspond to wires 180 Green and 200 Black. Turn on the key and measure the voltage between those two wires. Do you have 12v.? If you don't try going back to the fuse box and check that the fuse #7 (15-ampere) for the air ride seat is not blown.
Give both halves of the connector a good clean with some aerosol contact cleaner, hook everything up, and see how you go from there.

 

[Jobiss]

Thanks a lot! I’ll do it for sure. But since it happens only on steep slopes, I believe it has more to do with the switch cause then I put a little less weight on the seat. I’ll also try to figure out how to keep my weight to the switch while on steep slopes. But the thing is that I will not work on these slopes until next summer, so it’s only then that I’ll know if it works.
Thanks a lot for all your help!

 

[Nige]

What I’m thinking is if you can get your air-ride seat working it might also help to maintain pressure on the switch.

 

[Jobiss]

Yes, I think you’re right. The seat will follow my movements a little if the air-ride works. Thanks, I’ll work on it!

 

[KSSS]

You could maybe bank some snow on a slope and see if you have solved the problem.

 

[Jobiss]

That’s an idea. I think it may be to slippery on compacted snow, but I’ll give it a try. I have to admit that the slopes on my motocross track are very steep.
Thanks for the idea!