Meterless hydraulic system having load-holding bypass

A hydraulic system, comprising:

• a pump;
• a hydraulic actuator;
• first and second passages fluidly connecting the pump to the hydraulic actuator in a closed-loop manner;
• a control valve;
• and
• a load-holding valve associated with at least one of the first and second passages and configured to selectively lock movement of the hydraulic actuator, the load-holding valve comprising:
• a valve block at least partially defining:
• a pump passage in fluid communication with the pump;
• an actuator passage in fluid communication with the hydraulic actuator via the one of the first and second passages;
• a control passage in fluid communication with the control valve;
• a restricted passage fluidly connecting the actuator passage and the control passage;
• a bypass passage connecting the actuator passage and the control passage;
• and
• a valve element disposed within the valve block and movable between a first position at which fluid flow between the pump and the hydraulic actuator is blocked, and a second position at which fluid is allowed to flow between the pump and the hydraulic actuator, wherein the valve element is spring-biased toward the first position.

A hydraulic system, comprising:

• a tank;
• a pump;
• a hydraulic actuator;
• first and second passages fluidly connecting the pump to the hydraulic actuator in a closed-loop manner;
• a control valve;
• an operator interface device;
• a controller in communication with the control valve and the operator interface device;
• and
• first and second load-holding valves associated with the first and second passages, respectively, and configured to selectively lock movement of the hydraulic actuator, each of the first and second load-holding valves comprising:
• a valve block at least partially defining:
• a pump passage in fluid communication with the pump;
• an actuator passage in fluid communication with the hydraulic actuator via the first or second passages;
• a control passage in fluid communication with the control valve;
• a restricted passage fluidly connecting the actuator passage and the control passage;
• and
• a bypass passage connecting the actuator passage and the control passage;
• a check element disposed within the bypass passage and configured to allow fluid to flow in one direction from only the control passage to the actuator passage;
• and
• a valve element disposed within the valve block and movable between a first position at which fluid flow between the pump and the hydraulic actuator is blocked, and a second position at which fluid is allowed to flow between the pump and the hydraulic actuator, wherein the valve element is spring-biased toward the first position,
• wherein:
• the controller is configured to selectively cause the control valve to move between a first position at which the control passage is fluidly communicated with the tank, and a second position at which the control passage is blocked from the tank based on input from the operator interface device;
• when the control passage is fluidly communicated with the tank, the valve element of each of the first and second load-holding valves is allowed to move to the second position;
• and
• when the control passage is blocked from the tank, the valve element of each of the first and second load-holding valves is urged toward the second position.