Why does my tandem axle trailer not have a backup solenoid?

[Rupp]

Guys,
My tandem axle trailer doesn't have a lock out nor backup solenoid. Why? Is it because I have drum brakes?

 

[jimmbo]

Most Surge Brake Activators do have a Mechanical Lockout. Drum Brakes, by design, unless you are backing up up an Incline, you usually don't need to use it. Disk Brakes on the other hand, work very well in either Direction, so an Electric Solenoid, is needed, to prevent actuation

 

[04fxdwgi25]

Discs are the ones that require the back up lock out and 5 wire connector

 

[Scott Danforth]

Guys,
My tandem axle trailer doesn't have a lock out nor backup solenoid. Why? Is it because I have drum brakes?

yes, drum brakes do not lock up in reverse.

you only need a back-up solenoid with disc brakes.

 

[tpenfield]

If the trailer was previously equipped with what's known as 'free backing' drum brakes than it would not have the lock-out surge brake master cylinder.

Since disc brakes are the more common thing with new trailers, they come with the lock-out feature.

 

[Rupp]

Thanks for the info guys. I'm rebuilding my 23 year old trailer and the Brake Actuator Master Cylinder didn't have the electric solenoid and I wanted to make sure. My actuator doesn't have any lock out build in so I guess it's not needed? Thanks again.

 

[jimmbo]

Even with Drum Brakes, if you try backing up an Incline, unless you Physically Lock out the Actuator, the Brakes will be applied. Of course, if they are way out of Adjustment, you might get away with it

 

[04fxdwgi25]

Thanks for the info guys. I'm rebuilding my 23 year old trailer and the Brake Actuator Master Cylinder didn't have the electric solenoid and I wanted to make sure. My actuator doesn't have any lock out build in so I guess it's not needed? Thanks again.

Also keep in mind, the MC's that have the lockout are normally for disc. The MC internals for disc vs drum are quite different and should not be interchanged.

I am big fan of the superior stopping power of the disc brakes on all axles. They do need to be hydraulic actuated. But also a fan of electric brake controls.

The hydraulics call for a surge actuator, which I hate, so dumped the surge connector internals, locked it in place and converted to electric over hydraulic.
Great stopping power with great control..... Win-Win.

 

[dingbat]

Even with Drum Brakes, if you try backing up an Incline, unless you Physically Lock out the Actuator, the Brakes will be applied.

Free backing drum brakes do not require lockout.

Work well. Ran them before switching to disc with solenoid

 

[Lou C]

Drum brakes can be either free backing or non free backing. The free backing brakes have a single piston wheel cyl whereas the non free backing brake wheel cylinder has a dual piston wheel cylinder. If the trailer had an actuator with no back up solenoid it probably was equipped with free backing brakes. If it had non free backing brakes it would have been hard to back up without the solenoid because non free backing drum brakes do work in reverse.
I had two VWs with 4 wheel drum brakes and I can say for sure they work in reverse!

 

[KD4UPL]

My 2004 trailer with drum brakes didn't have a lock-out solenoid. It's uphill into my garage and I could not back it in there. The drum brakes were very effective up hill in reverse. I had a solenoid installed at a local trailer shop and now it works just fine to back the trailer up a grade.
The first thing I did when I got the trailer was take off the old 4 pin and put on a 7 pin connector. I hate dealing with adapters so I just put 7 pin on every trailer I own.