18
(1) Motion of brake stuff
The brake drum is pressed by the leading brake shoe and the secondary brake shoe with the
same force from subsidiary brake pump,when the top side of the brake shoe is stopped by the
fixed pin,the brake shoe will move toward brake drum until being stopped by the fixed pin,then the
friction between wearing piece and brake drum will increase. As the pressure the leading brake
shoe exerted on the secondary brake shoe is much larger than the subsidiary pump
pressure.Tthere will occur a quite large brake force. see figure 2-10
When driving backward,the brake stuff works in reverse to it when drives forward.
see figure 2-11
figure 2-10 motion when driving forward figure 2-11 motion when driving backward
(2) parking brake
The parking brake device which consists of pulling rod and pushing rod is assembled in wheel
brake stuff. The pulling rod,of which the action is transported to the side of secondary brake
shoe,is installed on the side of leading brake shoe.See figure2-12
(3) gap-self-regulating device
Gap-self-regulating device can keep a proper gap between wearing piece and brake drum,it
works only when driving backward.see figure 2-13.
figure 2-12 parking brake figure 2-13 gap-self-regulating device
(4) Motion of gap-self-regulating device
Brake the truck when driving backward,the secondary brake shoe gets contact to and roll
together with the leading brake shoe,making pulling rod rotating rightward around point A,see
figure 2-13,and B point rises. After the release of brake,pulling rod turns left under the force of
spring,Bpoint descending.with the increasing of the gap between wearing piece and brake
drum,the vertical distance of B point rotating grows,and the regulating device moves one tooth
space.,then,regulating rod gets longer
（
see figure 2-14
）
tthe gap narrows,regulating gap lies
between 0.4mm and 0.45mm.
1.pin
2.pull rod
3.active
hoof
1.adjusting
mechanism
2.spring 3.dragline
4.driven
hoof
5.jackstay
4.guide alot
5.pull
rod
Active hoof
Driven hoof
Active hoof
Driven hoof
