Commercial Vehicle Products

MADE IN U.S.A SINCE 1939

Modern Spring Brake Valve Exhaust Curve

To prevent spring brake drag the 110800, 110700, and 110500 are designed to retain pressure in the trailer’s spring brake chambers even with diminishing supply line pressure. The chart below shows typical response to a varierty of supply pressures

Supply Line

The supply line is the air line from the trailers towing unit (tractor) that is responsible for replenishing the air brake reservoirs. It also signals the trailer to go into emergency or park mode (spring brakes engaged) when the air pressure drops.

Spring Brake Chambers

This term is used to describe the portion of the brake actuators that are used to engage the brakes when the trailers is parked or goes into emergency lockup. Although integrally linked to the service brake actuators they are operated separately via the spring brake valve.

Typical chamber levels with diminishing supply line pressure

Supply Line	Spring Chamber
100	95
95	95
90	95
85	95
80	95

Supply Line	Spring Chamber
75	95
70	95
65	95
60	95
55	95

Supply Line	Spring Chamber
50	95
45	95
40	90
35	80
30	70

Supply Line	Spring Chamber
25	60
20	45
15	35
10	25
5	10

Phoenix, Arizona
Indianapolis, Indiana
602/253-1007
Fax 800/222-2334
www.sealcocvp.com