Ports C1 and C2, located on the forward and rear face of the height control valve (or on the rear top and bottom face of the integral dump valve), are the suspension ports.
(eg: 53321-Q120 Semi Trailer Leveling Valve )
Height Control Valve Port Functions
The ports (e.g., C1, C2) on a height control valve (HCV) are critical interfaces for connecting to a vehicle's suspension system. Their primary functions can be categorized as follows:
1. Core Functions
Dynamic Suspension Height Adjustment
By monitoring the relative position between the chassis and axle (e.g., due to load changes or road vibrations), the valve controls air flow through ports C1/C2-either inflating or deflating the air springs (airbags) to maintain a consistent ride height.
Example: When loaded, the valve supplies air to C1/C2 to raise the vehicle; when unloaded, it exhausts air to restore the preset height.
Manual Service Interface
In some designs, C1/C2 can be connected to diagnostic tools for troubleshooting or manual override.
(52341-Q135 Height Leveling Valve, 2938010-TR350 Trailer Height Control Valve)
2. Special Configurations
Models with Integrated Dump Valve
C1/C2 may directly link to rapid exhaust functions.
Port Usage Guidelines
Single-Port Applications
If only one air spring is connected (e.g., in a unilateral system), the unused port must be sealed with a 1/4-inch NPT plug to prevent air leaks and system failure.
Misconnection Risks
Swapping C1/C2 may invert suspension behavior (e.g., lowering instead of raising).
