Load Sensing Proportioning Valve (LSPV)
- Ensure unladen vehicle is on level ground. Ensure lever is not contacting stopper bolt. See Fig 1 .
- When lever is pushed toward valve, distance from LSPV lever hole and support hole must be within 6 55/64-6 15/16" (174-176 mm). If measured distance is not to specification, loosen support attaching bolt. Adjust support until measured distance is within specification.
- After measured distance is within specification, connect pressure gauges to input and output ports of LSPV. See Fig 2 . Bleed brake system. Refer to BLEEDING BRAKE SYSTEM in this article.
- Remove LSPV load sensing spring. Slowly depress brake pedal. See LSPV PRESSURE SPECIFICATIONS table.
- Install LSPV load sensing spring. Load weight into rear of vehicle until measured distance is 6 55/64" (174 mm) with lever slightly pressed in. See Fig 1
. Slowly depress brake pedal. See LSPV PRESSURE SPECIFICATIONS table.LSPV PRESSURE SPECIFICATIONS
Inlet Pressure psi (kg/cm2 ) Outlet Pressure psi (kg/cm2 ) 853 (60) (1) 242-327 (17-23) 1991 (140) (1) 370-526 (26-37) 1991 (140) (2) (3) 299-583 (21-40) (1) LSPV load sensing spring removed. (2) LSPV load sensing spring installed. (3) On vehicles with 2WD and heavy duty suspension, outlet pressure is 526-697 psi (37-49 kg/cm2 ). - If fluid pressure is not to specification, ensure all other brake system components are okay. If other components are okay, replace LSPV assembly.