Parking brake

[brian s]

Any one tried a line lock for a parking brake? On a m35a2 with a stock brake system?

 

[gimpyrobb]

They use them on the M108 cranes, I don't see why not on other models. I've been thinking of using an air cyl or linear actuator to set the one on my truck.

 

[brian s]

After thinking about it I don't know if it would work because you would have to keep the solenoid under power when applied

 

[gimpyrobb]

Same with air leak down, thats why I was thinking linear actuator.

 

[porkysplace]

I think it would be good to use long enough to choke the tires , but would want to leave pressure on the system for long periods of time when not near the vehicle. Most wreckers I have drove have had them but was more to lock the brakes for winch outs and we also used steel plates chained to the back of the bed for wheel chokes to keep the wrecker from sliding when winching .

 

[brian s]

Same with air leak down, thats why I was thinking linear actuator.

i thought that the air just made it so you could apply the brakes. once applied and locking the line i did not think air would matter!!
i could be wrong.

 

[porkysplace]

i thought that the air just made it so you could apply the brakes. once applied and locking the line i did not think air would matter!!
i could be wrong.

Your right air leak down wouldn't matter as they get install after the master cylinder and hold pressure from the Mico-lock to the wheels.

 

[VPed]

How about using a spring brake chamber from a big truck as the actuator, air to release and applied by venting.

24 VDC linear actuators in various strokes and ratings are available pretty cheap on surpluscenter.com

 

[Wildchild467]

If you have the engine running during operations, then why not do a modification to the air pack to pressurize it so that it locks up all the wheels? There was a modification done somewhere that people use for when towing a deuce, you can apply the brakes on the towed deuce by the trailer brake line from the towing vehicle. Do something similar. Just pressurize it with a specific amount of air pressure and it will lock the wheels up. Just have to make something redundant do you don't bump the switch/valve while going down the road. I wouldn't mind doing this modification myself. It would be handy.

I don't know how that electric brake valve works with the hydraulic brake wreckers. Is it similar to how line locks work on drag cars?

 

[porkysplace]

If you have the engine running during operations, then why not do a modification to the air pack to pressurize it so that it locks up all the wheels? There was a modification done somewhere that people use for when towing a deuce, you can apply the brakes on the towed deuce by the trailer brake line from the towing vehicle. Do something similar. Just pressurize it with a specific amount of air pressure and it will lock the wheels up. Just have to make something redundant do you don't bump the switch/valve while going down the road. I wouldn't mind doing this modification myself. It would be handy.

I don't know how that electric brake valve works with the hydraulic brake wreckers. Is it similar to how line locks work on drag cars?

They just shut a valve with pressure on the system and hold the pressure , when you release it the fluid goes back to the MC.

 

[Wildchild467]

They just shut a valve with pressure on the system and hold the pressure , when you release it the fluid goes back to the MC.

The only bad thing about them is that the valve can leak down a little and lose pressure on the brakes. It happened to me with my Hurst Line Lock that I have on my Street Rod. It would leak down holding the front brakes locked up. I rebuilt it with a new O-ring and it was all better. If you pressurized the air pack, it would keep the same pressure on the system all the time. It would not be for long term and should not solely be relied on, but it would work well for winching operations while using the parking brake. one just had to know the limits of the system. Don't just pressurize the air pack and use it as a parking brake with the truck not running. Then air leaks down and your truck rolls away.

 

[dmetalmiki]

That is what I used an my old deuce. For parking only. It works onto the foot brake linkage. On my other deuce with tow palm couplings modification, an air operated cylinder applies the brakes on the same linkage when the tow vehicles brakes are applied.

 

[rustystud]

The only bad thing about them is that the valve can leak down a little and lose pressure on the brakes. It happened to me with my Hurst Line Lock that I have on my Street Rod. It would leak down holding the front brakes locked up. I rebuilt it with a new O-ring and it was all better. If you pressurized the air pack, it would keep the same pressure on the system all the time. It would not be for long term and should not solely be relied on, but it would work well for winching operations while using the parking brake. one just had to know the limits of the system. Don't just pressurize the air pack and use it as a parking brake with the truck not running. Then air leaks down and your truck rolls away.

That's a very interesting idea you have there ! It would be really easy to do too since there is already extra ports drilled into the valve area.

 

[Wildchild467]

That's a very interesting idea you have there ! It would be really easy to do too since there is already extra ports drilled into the valve area.

I forget the exact process to plum the air to do this. It was listed somewhere else in a thread that discussed how to hook up a glad hand in the front of a deuce to operate the brakes... similar to how the 5 ton trucks do it.