the_fbi
|
 posted on 16/4/06 at 11:17 PM |
|
|
Hydraulic brakes on trailers
How do these work?
There appears to be a MC, normally mounted rearwards of the dolly wheel, but how is this fed?
Is it something weird like the tow hitch is connected to the MC pushrod so as the car slows it pushes in the pushrod which acts on the MC which brakes
or is that far too clever?
One of those strange things which has niggled me for a weekend.....
|
|
|
|
|
ReMan
|
| posted on 16/4/06 at 11:25 PM |
|
|
Weirdly thats exactly how they work!
www.plusnine.co.uk
|
|
|
JoelP
|
| posted on 16/4/06 at 11:26 PM |
|
|
your pushrod idea would actually be linked brakes i believe, normal trailers with brakes have a compressable section in the hitch, which pumps the
fluid. Much the same as normal trailer brakes, ie rods or cables. 
edit: i read that as the main cars brakes are linked to the trailers brakes via a pushrod, which would be linked brakes. You are infact correct as is
[Edited on 16/4/06 by JoelP]
|
|
|
the_fbi
|
| posted on 17/4/06 at 08:48 AM |
|
|
Quite a simple but ingenious way of doing it.
There must be some gotchas with MC size and friction required on the hitch but I guess that could be easily sorted with a bias valve and a return into
the MC.
Also helps explain why trailers are so expensive 
|
|
|
zilspeed
|
| posted on 17/4/06 at 09:06 AM |
|
|
Indeed.
But they are self regulating after a fashion. Too much braking effort slows down the trailer which releases the brakes - which allows the trailer to
gather speed which re-applies the brakes which slows the trailer etc...
That's why you sometimes get a bit of chatter under braking.
|
|
|
DEAN C.
|
| posted on 17/4/06 at 09:23 AM |
|
|
Hi,although I think you are ok on older trailers I believe it is now illegal to build trailers with hydraulic brakes.
My personal experiance with these is that they tend to seize or rip the seals apart after being stood for months at a time, and collect water due to
being in the elements.
Having said that if you keep an eye on them and change the fluid regular then they should be ok.
Regards,Dean...........
Once I've finished a project why do I start another?
|
|
|
Syd Bridge
|
| posted on 17/4/06 at 09:27 AM |
|
|
Put a stiff shock absorber behind the hitch pushrod. This keeps the brakes smooth and they don't grab. Also allows you to dab the car brakes to
get the trailer's to work, then if you ease off the car brakes you should feel the trailer brakes slowing the whole rig up. Keeps things
straight and safe.
I've done them like this for many years.
I also drew up an active system using vacuum, but not fitted into and activated by the vehicle hydraulic system as others are. It used a vacuum
regulator/valve connected to the brake pedal. It worked, but took a looong time to adjust properly.
Cheers,
Syd.
|
|
|
