Pneumatic Load sensing valve

The automatic load sensing valve ( LSV )–pneumatically controlled, is installed in vehicles ( motor vehicles, trailers and articulated trailers ) with pneumatic braking systems and pneumatic suspensions. The braking pressure in the pneumatic braking system, and with that the braking force, is controlled to correspond to the static load condition of the particular vehicle. When the static load changes, the pressure in the suspension bellows changes continuously via the pneumatic suspension valve. This pressure is used to simultaneously control the connections 41, 42 of the LSV. The effective, easily reconstructed in the workshop, pressure ratio iR = pe1: pe2 is the practical reference point for the adjustments.

Installation

The LSV is fixed to the vehicle chassis with two M 8 bolts. The vent must point downwards. The pneumatic lines have to be connected according to the Port markings 1, 2, 41, 42. The values of the settings have to be stamped on the accompanying LSV information plate Part. No. 028 0280 09. The information plate must not be capable of becoming detached and must be attached to the vehicle where it is easily visible (German road traffic licensing regulation: StVZO - SP - Rili. - 2.5).

Function

Pneu LSV Internal for Function.png

 

The connectors 41 and 42 of the actuating cylinder are attached to the connecting lines of the pneumatic suspension valves/bellows on the right and left sides of the vehicle. The pistons in the actuating cylinder are held in the end position when the vehicle is empty (suspension pressure empty connections 41, 42).

When the vehicle is loaded and the pressure rises at the connections 41 and 42, the control pistons and the slider (1) attached to them by the connecting rod are shifted to the right which results in a change in the effective movement translation ratio. The translation movement between the pistons and balance arm is so adjusted that with suspension pressure empty the control inlet brake pressure pe1 at connection 1 is transferred to the outlet control pressure at connection 2 but reduced by the pressure ratio iR.

The system is normally designed so that in the loaded position the controlled inlet pressure in connection 1 remains unmodified, i.e. the controlled outlet pressure at connection 2 is in 1:1 relation to it.

The LSV is fitted with a proportional control characteristic that has a start pressure control (pD) of approx. 0.4 bar in the uncontrolled range to overcome the start force (valves, wheel brakes) The LSV works “statically”, i.e. a change in the pressure ratio, e.g. from a change in suspension pressure following a change in axle loading, is suppressed during braking.

 

Maintenance

  • Function and leak test
  • Check that pe2 empty and pe1 loaded correspond to the data on the LSV instruction plate.
  • It is mandatory that the LSV be so mounted that it is in a vertical position and the vent point downwards during examination and adjustment

Simulation connection

  • Variable installation (good access)
  • Makes it possible to test to EG/ECE as well as the German § 29 StVZO

11 = Air IN (bellows)

12 = Air IN (filling connection)

2 = Air OUT (LSV 41/42)

Technical data

  • Operating pressure: pe max 10 bar
  • Operating temperature range: - 40°C to + 80°C
  • Ports: 1, 2: M 16 x 1.5
  • 41, 42: M 12 x 1.5
  • Port 1 = Service Brake Air IN
  • Port 2 = Service Brake Air OUT
  • 41 = Air Suspension, Control connection 1
  • 42 = Air Suspension, Control connection 2