Towing the Coach - SMC Magnum Chassis

[Jim Casazza]

We have been away from the RV scene for a few years, but have decided to clean up the coach and get back on the road (at least for some short term trips).  Hope to maybe catch up with a few old BAC friends as well!

Anyway, this week, I was driving our '99 Patriot Thunder down the interstate and all seemed well until I got of the the exit and ran a few miles down a local road.  The coach started to lose power, then stalled as I approached a traffic light.

I could not get the coach restarted, even after changing the fuel filter (and filling with fuel), so we needed a tow. 

Somewhere in the back of my mind I seem to think I read something about towing this coach and the the emergency brake being an issue.  The tow driver did disconnect the driveshaft, but I told him I was pretty sure there was an issue if he towed the coach without addressing the parking/emergency brake.  Since I couldn't remember, we decided to run an air line down the coach (from his truck) to my air fitting in the engine bay to keep pressure in the system.

So, I'm wondering if I was imagining this "brake issue" or it is something that does need to be addressed.  Would disconnecting the drive shaft be sufficient?  I'm not sure if the brake is on the transmission side or axle side of the driveshaft?

BTW, My towing experience is a whole other story, but suffice to say I will cancel my Good Sams towing and never recommend it to anyone.

[Mike Shumack]

Our coaches have air brakes, and the parking brake (a.k.a. emergency brake) uses a large spring to apply the rear brakes. Air pressure is used to compress the spring and release the brakes when the parking brake button is pushed in. If the coach does does not have over 65 psi air that emergency brake will automatically come on.

So if your needing to tow the coach, you need to have air pressure to keep the brakes released. Most of our coaches leak air so towing without providing additional air (the air line from the tow truck) is risky because if enough air leaks out of the coach while towing the brakes will come on.

There is also a mechanical way to release the brakes. It's called "caging the brakes". There is a "tee-head threaded rod" with a nut  (usually stored in a holder built into the brake chamber) that can be inserted into the brake chamber and then the nut is tightened which compressed the spring and releases the brake. If you do this, then you don't need to worry about having/keeping air in the system.

Running an air line from tow truck to coach to keep coach's air tanks full, is usually easier.

The other thing to know about towing - is that if the rear wheels are on the ground when towing, either the driveshaft should be disconnected or the axle shafts should be pulled, so the rear axle is not turing the transmission while towing (which is bad for the transmission when the engine is not running).

Sorry if my response is a little long winded.

[Gerald Farris]

Jim,
Your 99 Thunder parking brake is on the rear axle side of your drive shaft, so it will be engaged and restrict rear wheel rotation unless you maintain at least 65 PSI in your air system. Without air pressure, you would have to disable or remove the parking brake caliper to tow the coach.

Gerald

[Mike Shumack]

Jim,
Your 99 Thunder parking brake is on the rear axle side of your drive shaft

I did not know about this style brake.
I 've seen mechanical drum type parking brakes on drive shafts - but not what Gerald describes.
I like/try to help when I can, but seems I was wrong about this. Sorry Jim.

[Jim Casazza]

Thank you to both members for such a quick reply. 

I was pretty sure I remembered that tidbit of info about the brake, so glad I had them run the air line.

I think I'll buy a 75' air line to keep on board, just in case. 

[Joel Ashley]

It’s disconcerting that the tow driver, even though he must’ve been using a truck large enough, didn’t on his own seem to know he’d need to attach his airline.  Unfortunately no matter what club-subscribed tow program you use, they could contract with the same tow company, especially if it’s the only local one.  Good job, Jim, being a vigilant owner and retaining what you’ve read here... regrettably that’s too often more than I can say.

Joel