I have a Grove RT-60S. It has an airbrake system much like any truck with air brakes. Two pancake brake chambers and two spring brake chambers. When I push the parking valve in the cab, air pressure goes through the swivel fitting into the spring brakes and disables parking brake, just like on any truck. The problem is that as soon as I push the PARKING brake valve, air starts coming out of the SERVICE BRAKE valve. I did some troubleshooting and disconnected and capped the air hose for parking brake, coming out underneath of the swivel. So all valving or such that accepts parking brake air, is not involved. The air still comes out of the service brake pedal. However if I cap the parking brake line coming INTO the swivel, on the top side of the crane, then such behavior (not surprisingly) stops. So, I conclude that the swivel is leaking parking air into the service air. I did locate both the parking and service air hoses coming into the swivel and they are next to each other, so I am not that surprised that one leaks into another. My question is what should I order and replace as a replacement part? The whole swivel assembly? Or just some rings? My service manual is silent on all air brake functionality.
If you pull it apart just change all the seals. Make double sure all your wires are marked correctly. I fixed that exact same problem on an rt60s back when I wore a younger mans clothes. If I remember right the air and transmission controls run though the small can on top. If your not having trouble with the hyd swivel just pull the top can and change those seals.
Knepptune, thank you VERY much for sharing your experience! This is overall a great crane, and simple too, I am just ironing out the small stuff so that I can use it in a trouble free manner. The electric swivel should be easy to remove as all wires are clearly marked. Going along with what you said, I was surprised that some hoses to the top can had what looked like trans fluid to me, now I am guessing it makes sense with trans controls. I will take off the electrical swivel, and do seals on the pneumatic (top) can as you said.
OK, here's another question.If I take the swivel apart to do the pneumatic part, should I perhaps do the bottom swivel as well? The hydraulic one? Is that also about just changing seals? Just to be done with it all at once?
If it was me and the hydraulic swivel wasn't leaking (much) I would just leave it be, let sleeping dogs lie, you know? But then I'm the laziest workin' man I know..... :sleeping
I would probably agree to this. I'm thinking the hydraulic swivel has more or less nice clean oil lubricating the seals keeping everything nice and happy. Where the swivel that carries the air system can have all that nasty crap that an old poorly maintained air system will contain.
Right, the air system is full of disgusting stuff. Thanks, guys, for your collective wisdom.
Just a little update. I called Walter Payton and ordered a seal kit for the pneumatic swivel. I also decided to do the hydraulic swivel at the same time. I know that all those seals, even if they are not already leaking, are on borrowed time. Better to fix them in advance.