Trailer Drum Brake Question

[hd883chopper]

(27' Trail-Rite Tandem w/ surge drum brakes)

Hey there, got a issue I was hoping some of you could shed some light on.

I'm not an expert with drum brakes but I think I know the basics. I'm changing the pads, repacking new bearings, adding new seals and races. All the fun stuff.

My question is this. I noticed all four of my drums had a single piston wheel cylinder. Where as most automotive drums were dual piston. My single piston applies pressure to the front pad (pad closest to the trailer tongue). In my opinion, this would not exert any pressure on the rear pad and therefore the only thing braking the trailer is the front pads.

Why would it only have one piston to apply to one pad? What about the rear pad? Did I buy new rear pads for nothing?

Thanks,
HD

 

[dwco5051]

Re: Trailer Drum Brake Question

This makes the brakes self energizing. The front pad should be smaller than the rear pad. As the front pad makes contact with the drum it applies force to the rear pad and acts like a "power assist" by using the forward momentum of the trailer to apply more pressure to the rear pad. Since you are not going to apply the trailer brakes at high speed in reverse one cylinder on one shoe does all the braking that is necessary.

 

[hd883chopper]

Re: Trailer Drum Brake Question

Thanks for the explanation. I was just concerned that perhaps I wasn't getting the braking power at the wheel that I should be getting. But I guess I'm good to go.

Thx again.
HD