Closed level control system for a vehicle

A closed level control system for a vehicle having a vehicle body, vehicle axles and pressurized medium chambers with which the vehicle body is suspended relative to corresponding ones of said vehicle axles, the closed level control system comprising:

• a pressurized medium supply vessel for holding a medium under pressure as a pressurized medium;
• a pump for transferring said pressurized medium between said supply vessel and said pressurized medium chambers;
• said pump having an input and an output and said pump being configured so as to permit said pump to pump said pressurized medium from said input to said output thereof;
• a first controllable directional valve switchable between a base state and a switched state;
• a second controllable directional valve switchable between a base state and a switched state;
• a changeover valve switchable between first and second states;
• a first pressurized medium line connected to said supply vessel and being connected via said first controllable directional valve to said input of said pump;
• a second pressurized medium line connected to said pressurized medium chambers and being connected via said changeover valve to said output of said pump at least when said pressurized medium is to be transferred by said pump from said supply vessel into said pressurized medium chambers;
• control means for switching said first controllable directional valve into said switching state thereof and said changeover valve into said first switching state thereof to cause said first pressurized medium line to be connected to said input via said first controllable directional valve and said second pressurized medium line to be connected to said output of said pump thereby facilitating a transfer of said pressurized medium by said pump from said supply vessel into said pressurized medium chambers;
• a third pressurized medium line connected to said pressurized medium chambers and being connected via said second controllable directional valve to said input of said pump;
• a fourth pressurized medium line connected to said supply vessel and being connected via said changeover valve to said output of said pump at least when said pressurized medium is to be transferred by said pump from said pressurized medium chambers into said supply vessel;
• said control means functioning to switch said second controllable directional valve into said switched state and said changeover valve into said second state thereby facilitating a transfer of said pressurized medium by said pump from said pressurized medium chambers into said supply vessel;
• a single pressure sensor mounted in said third pressurized medium line;
• said single pressure sensor being connectable to said first and fourth pressurized medium lines via said first and second controllable directional valves;
• and,
• ancillary valve means switchable between a first position wherein said single pressure sensor is connected to at least one of said pressurized medium chambers for measuring the pressure therein and a second position wherein said single pressure sensor is connected to said pressurized medium supply vessel for measuring the pressure therein.

A closed level control system for a vehicle having a vehicle body, vehicle axles and pressurized medium chambers with which the vehicle body is suspended relative to corresponding ones of said vehicle axles, the closed level control system comprising:

• a pressurized medium supply vessel for holding a medium under pressure as a pressurized medium;
• a pump for transferring said pressurized medium between said supply vessel and said pressurized medium chambers;
• said pump having an input and an output and said pump being configured so as to permit said pump to pump said pressurized medium from said input to said output thereof;
• a first controllable directional valve switchable between a base state and a switched state;
• a second controllable directional valve switchable between a base state and a switched state;
• a changeover valve switchable between first and second states;
• a first pressurized medium line connected to said supply vessel and being connected via said first controllable directional valve to said input of said pump;
• a second pressurized medium line connected to said pressurized medium chambers and being connected via said changeover valve to said output of said pump at least when said pressurized medium is to be transferred by said pump from said supply vessel into said pressurized medium chambers;
• control means for switching said first controllable directional valve into said switching state thereof and said changeover valve into said first switching state thereof to cause said first pressurized medium line to be connected to said input via said first controllable directional valve and said second pressurized medium line to be connected to said output of said pump thereby facilitating a transfer of said pressurized medium by said pump from said supply vessel into said pressurized medium chambers;
• a third pressurized medium line connected to said pressurized medium chambers and being connected via said second controllable directional valve to said input of said pump;
• a fourth pressurized medium line connected to said supply vessel and being connected via said changeover valve to said output of said pump at least when said pressurized medium is to be transferred by said pump from said pressurized medium chambers into said supply vessel;
• said control means functioning to switch said second controllable directional valve into said switched state and said changeover valve into said second state thereby facilitating a transfer of said pressurized medium by said pump from said pressurized medium chambers into said supply vessel;
• a pressure sensor mounted in one of said second and third pressurized medium lines;
• and,
• a third controllable directional valve connected between said pressure sensor and said pressurized medium chambers and being switchable between a base state wherein said pressurized medium chambers are separated from said pressure sensor and a switched state wherein said pressurized medium chambers are connected to said pressure sensor.