Variable delivery control arrangement for a pump

A method of controlling the delivery of fluid from an outlet port of a pump to a work system, comprising:

• connecting a pressure reducing valve to the outlet port of the pump in parallel with the work system;
• providing a fluid delivery changing mechanism associated with the pump that has first and second fluid ports;
• connecting the reduced pressure from the pressure reducing valve to the first fluid port of the fluid delivery changing mechanism;
• locating an infinitely variable control valve arrangement having first and second end portions between the reduced pressure of the pressure reducing valve and the second fluid port of the fluid delivery changing mechanism to control the flow of reduced pressure fluid to the second fluid port;
• connecting a low pressure conduit having a flow restrictor therein to the reduced pressure from the pressure reducing valve;
• locating an electrically controlled proportional valve in the low pressure conduit downstream of the flow restrictor;
• and
• connecting the reduced pressure from the pressure reducing valve to both the first fluid port and the first end portion of the infinitely variable control valve arrangement and connecting the second end portion thereof to the low pressure conduit at a location between the flow restrictor and the electrically controlled proportional valve.

A variable delivery control means for controlling the volume of fluid being delivered to a work system, comprising:

• a fluid pump having an outlet port;
• means for changing the delivery of the fluid from outlet port of the fluid pump, the changing means includes first and second fluid ports;
• means for reducing the pressure of the fluid from the pump to a control conduit, the pressure reducing means being connected in parallel with the work system;
• a low pressure conduit connected to the control conduit downstream of the reducing means;
• means for restricting flow downstream of the pressure reducing means, the restricting means being disposed in the low pressure conduit;
• infinitely variable valve means for controlling fluid flow between the pressure reducing means and the second fluid port of the flow changing means, the infinitely variable valve means has first and second end portions and is disposed in the control conduit;
• a proportional valve means for controlling fluid flow through the low pressure conduit, the proportional valve means being disposed in the low pressure conduit at a location downstream of the pressure reducing means;
• a first pilot conduit means for directing fluid flow from the reducing means to both the first end portion of the infinitely variable valve means and the second port of the flow changing means;
• and
• a second pilot conduit means for directing fluid flow between a point downstream of the restricting means to the second end portion of the infinitely variable valve.