Yes, the way it is normally set up, it uses a 12v solenoid to hold pressure at the front brake lines so that the rear tires can be spun in the water box to heat the rubber before a drag strip launch. There are other manual types that you can plumb into the rear or front lines if you're thinking about using it as a park brake.
We used a hydraulic ball valve as a sort of line lock on my son's 455 Olds powered Luv truck. We mounted it in the line to the rear brakes and drilled a hole in the floor of the truck just to the left of the seat. In normal driving, the valve was left in the open position, but when he wanted to heat the tires, he simply turned the valve handle 90 degrees to the off position, thus preventing passing any fluid to operate the rear brakes. Holding the foot brake down only activated the front brakes to hold the truck in the water box. After the burnout, he turned the valve back to open so he had 4-wheel brakes again. Sort of a poor man's line lock. It worked well as a park brake also, just jam the brake pedal, turn the valve to closed and fluid pressure remained in the rear line to lock the rear brakes.
Last edited by techinspector1; 07-19-2007 at 09:06 PM.