Drum Brake Operation
The brake fluid lines
The drum brake systems are used in most trucks
Before bleeding brake system, start the engine to increase the air pressure at a high level to bleed the brake.
The brake fluid lines
Sequential brake bleeding
To bleed the brakes, we need to get the air out in a sequence of auto parts from near to far.
Starting from -brake booster - right front wheel - left front wheel - right rear wheel - left rear wheel (between the space of brake booster)
Bleed the brakes in accordance with gravity by filling up the oil. Then remove the nut to bleed the brake. Wait until the brake fluid flows out. After that, tighten the nut in accordance with gravity. It will flow from high to low to bleed the air out of the system. Then bleed the brakes regularly.
(This method is applicable to small cars. The path of the brake water is not complicated. It may take a long time to finish.)
Brake Bleeding
Fill enough brake fluid to bleed brake. (Don’t let brake fluid run out during bleeding)
Remove rubber stopper out of bleeding screw. Then check and clean the bleeding screw. Apply a wrench to loosen and tighten it.
After that, join the tip of colorless silicone tube with the bleeding screw and put the other tip in a colorless container.
Press brake pedal repeatedly. Then keep stepping on it.
Loosen the screw half-round to allow the brake fluid containing air bubbles to flow into the container. Then tighten the screw immediately.
Release brake pedal slowly and repeat 3rd and 4th steps until the brake fluid from pipe has no air bubbles. After choking, install the rubber to its position. When the operation stops, the brake fluid should be refilled enough for use.
(source: Repair service center P Machpro Co., Ltd.)