Trailer parking HYDRAULIC brake.

[Reg]

My thoughts exactly. I fail to see the point of it.

Can someone identify any vehicle that uses hydraulic parking brakes rather than mechanical?

There are full mechanical line-locks available that you'd have to activate at the tongue.

Yes, no, and lets not bother with the "why ?" and "I think you don't need this" ?
I started the thread looking for suggestions on "How to", not "why would you ?" and/or "You're nuts",
which may be true but that is incidental.
Thanks for the concerns anyway.
I just don't want to devolve into endless justifications and counter arguments.

I have an electric actuator on the trailer, these are NOT hydraulic surge brakes.
As I said in an earlier post, I acknowledge that this is NOT a substitute for wheel chocks.
THOSE and the landing gear are what would prevent it from rolling away if/when it was parked at the top of a steep hill for several months and the hydraulic pressure finally leaked down enough to let it go.

Right now I think the best solution is a diverting valve, which could be manual or electric.
On the parking brake side I may or may not decide to figure a way to maintain hydraulic pressure for long periods, e.g. an air tank.

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hint/clue: Ever try to park a HEAVY (relative to its tow vehicle) trailer on a steep loose surface ?

 

[CDN Farm Boy]

Let me see if I have this right:
1) You have electrically activated hydraulic brakes on the trailer
2) You want to be able to park the tow rig/trailer combo and activate a parking brake on the trailer from within the cab.
3) You also want this system to work with the trailer parked by itself
4) type of tow vehicle and trailer have been left unidentified (to presumably open more ideas but also leads to confusion and additional questions)

 

[Reg]

Let me see if I have this right:
1) You have electrically activated hydraulic brakes on the trailer
2) You want to be able to park the tow rig/trailer combo and activate a parking brake on the trailer from within the cab.
3) You also want this system to work with the trailer parked by itself
4) type of tow vehicle and trailer have been left unidentified (to presumably open more ideas but also leads to confusion and additional questions)

1 check
2 not necessarily from WITHIN, at the side of the trailer would be acceptable.
3 check
4 partly to keep discussion open, though more to avoid tangents and DEEP rat holes, e.g. "wadda Ya wanna put those in a trailer like that for ?"

I posted in the hydraulics forum because I didn't want to get into the vehicle aspects, or I would have posted it in Transportation and Trailers.
I probably should have posted it as a simple hydraulics question and left the whole trailer aspect out of it.

Anyway, it sits on two 8,000 lb Dexter axles that now have 13 inch Kodiak discs on them.
WAYyyyyyy better than the hydraulic drums it had previously.
The actuator is a Carlisle Hydrastar 1600 psi.
The tow vehicle is irrelevant, it just supplies a 7 pin socket with a brake control wire (traditionally blue) and aux 12V
a Tekonsha brake controller is in the cab and for all that knows or cares the trailer has 1920s era electric drum brakes.

 

[CDN Farm Boy]

Sounds to me that a mechanical line lock would be the best choice for you.

If memory serves some early 5 tons (70's International?) had one that was a simple flip of a lever to activate. Flip the lever to "on" and apply the brakes and it works like a one way valve to keep them applied. Flip the lever to off and you are good to go.

Since you have the electric activated hitch, perhaps you could wire in a switch at the hitch to activate the brakes with one hand then using the other hand to turn a standard line lock (I've seen them much line a 1/4 turn ball valve)

 

[94BULLITT]

It would be a 2 person job to lock the brakes with a mechanical lock. One to hit the brakes on the tow rig and one to lock it on the trailer.

 

[Reg]

Another way to activate the trailer brakes is to pull the breakaway pin.
(or short across the breakaway switch)

This is how I bleed them;
Hook a long spool of "bell wire" to the back of the breakaway switch contacts,
unroll it to the axle ends I am working on, connect the two ends together to simulate
the pulled pin (the pump starts), bleed, close, disconnect (the pump stops), repeat at each wheel.

I could as easily wire a switch or push button across them and mount it wherever
I decide is convenient. I could have one each side, I could have MANY of them.

That may make it a two HANDED job, but not a two PERSON job.

Anyway, it is more of an hydraulics puzzle than a "brakes" puzzle.
I think leak down would be minimal, but I am still considering the possibility
of maintaining pressure with an air tank. "Air over hydraulic" ?

 

[CNC Dan]

Could you add a check valve between the actuator and the brakes? That would cause the brakes to stick on after they are applied. So then you need to add two tee fittings. One on each side of the check valve. The tees then go to a solonoid valve that is normaly closed or normaly opened, your choice. When the valve is opened, you have normal opperation, with the valve closed, applying the brakes will set the "parking brake".

 

[aczlan]

Some solenoid valves at Surplus Center block in one direction only... Might be worth looking into.

Aaron Z

 

[firemanmike69]

How about a 3 way hydraulic valve and a porta-power to apply pressure? Get out throw the valve, pump up the porta-power which should have its own valve to prevent pressure from bleeding off, then the brakes are set. When your ready up leave flip the valve on the porta-power then throw the 3 way valve and your back to business as usual

 

[wdchyd]

How about a 3 way hydraulic valve and a porta-power to apply pressure? Get out throw the valve, pump up the porta-power which should have its own valve to prevent pressure from bleeding off, then the brakes are set. When your ready up leave flip the valve on the porta-power then throw the 3 way valve and your back to business as usual

I've seen this on older trail groomer machines on ski mountains up this way.......they would use a porta-power with a nitrogen accumulator (your air-over-hyd) tee'd in the line to make-up for pressure losses......but some sort of valve is needed to isolate this setup during normal brake operation