A hydraulic apparatus configured to supply track-setting devices for producing a cross-country skiing trail; the apparatus comprising: a first inlet configured to receive a fluid; a first outlet and a second outlet configured to release two flows of fluid; a first hydraulic coupling motor having a second inlet, a third outlet and a first shaft; and a second hydraulic coupling motor having a third inlet, a fourth outlet and a second shaft; wherein the second inlet and the third inlet are connected to the first inlet, and the first shaft and the second shaft are integrally connected to each other, the third outlet being connected to the first outlet, and the fourth outlet being connected to the second outlet.

In one aspect, a piston assembly for a fluid-driven actuator may include a piston defining a passage extending between first and second chambers of the actuator. The piston assembly may further include a valve having a valve head and a valve stem. The valve may be positioned within the passage and slidable between an open position and a closed position. The valve stem may extend outward from the passage into the second chamber when the valve is positioned in the closed position. Additionally, the piston assembly may include a spring compressed between the valve head and the piston. The spring may be configured to bias the valve to the closed position. The valve may be configured to move to the open position when a pressure in the second chamber exceeds a pressure threshold or when the valve stem contacts a cylinder of the fluid-driven actuator.

In one aspect, a system for rephasing fluid-driven actuators includes a plurality of fluid-driven actuators fluidly coupled together in series. A controller is configured to monitor a position differential existing between current positions of rods of the actuators relative to a differential threshold based on sensor measurements. The actuators are out-of-phase when the monitored differential exceeds the threshold. The controller is also configured to initiate a flow of fluid to the actuators to rephase the actuators when the monitored differential exceeds the threshold. The controller is further be configured to continue to monitor the differential following initiation of the flow of fluid to the actuators. Additionally, the controller is configured to implement a control action associated with terminating the rephasing of the actuators when the monitored differential remains constant after a first time period has elapsed following initiation of the flow of fluid.

In one aspect, a system for rephasing fluid-driven actuators includes a plurality of fluid-driven actuators fluidly coupled together in series. A controller is configured to monitor a position differential existing between current positions of rods of the actuators relative to a differential threshold based on sensor measurements. The actuators are out-of-phase when the monitored differential exceeds the threshold. The controller is also configured to initiate a flow of fluid to the actuators to rephase the actuators when the monitored differential exceeds the threshold. The controller is further be configured to continue to monitor the differential following initiation of the flow of fluid to the actuators. Additionally, the controller is configured to implement a control action associated with terminating the rephasing of the actuators when the monitored differential remains constant after a first time period has elapsed following initiation of the flow of fluid.

A tracked vehicle includes a pilot control module which enables the pilot to steer the tracked vehicle using an existing joystick of the tracked vehicle. The tracked vehicle also includes a dual track drive pedal which drives the tracks of the vehicle simultaneously. The joystick is used to make steering corrections when utilizing the dual track drive pedal.

A tracked vehicle includes a pilot control module which enables the pilot to steer the tracked vehicle using an existing joystick of the tracked vehicle. The tracked vehicle also includes a dual track drive pedal which drives the tracks of the vehicle simultaneously. The joystick is used to make steering corrections when utilizing the dual track drive pedal.

A double-rod ram (1), preferably for an extruder, comprising an outer cylinder (10), an inner cylinder (20) installed therein and arranged concentrically therewith, a double-acting work piston (41) provided in the inner cylinder to be displaceable and a bypass device (50) with at least one bypass valve (52), wherein the work piston (41) divides the inner cylinder (20) into two compartments (42) and can be loaded with a hydraulic fluid from both compartments (42), wherein the bypass device (50) is so arranged that in a bypass position of the bypass valve (52) a fluid connection between the two compartments (42) is formed by a direct connection, preferably at least one bypass line, and in a work position of the bypass valve (52) no such fluid connection is present.

A double-rod ram (1), preferably for an extruder, comprising an outer cylinder (10), an inner cylinder (20) installed therein and arranged concentrically therewith, a double-acting work piston (41) provided in the inner cylinder to be displaceable and a bypass device (50) with at least one bypass valve (52), wherein the work piston (41) divides the inner cylinder (20) into two compartments (42) and can be loaded with a hydraulic fluid from both compartments (42), wherein the bypass device (50) is so arranged that in a bypass position of the bypass valve (52) a fluid connection between the two compartments (42) is formed by a direct connection, preferably at least one bypass line, and in a work position of the bypass valve (52) no such fluid connection is present.

A system and method for deploying a flight control surface. The method includes displacing actuators engaged with the flight control surface during an initial period wherein each actuator displaces from zero speed to a deployment speed, and during a deployment period after the initial period. The method includes during the deployment period, controlling displacement of at least one of the actuators in response to actuator status information received therefrom. The method includes during the initial period, limiting an acceleration of said actuator from the zero speed to the deployment speed. The system has a control unit with a force fight controller and an acceleration limiter.

A system and method for deploying a flight control surface. The method includes displacing actuators engaged with the flight control surface during an initial period wherein each actuator displaces from zero speed to a deployment speed, and during a deployment period after the initial period. The method includes during the deployment period, controlling displacement of at least one of the actuators in response to actuator status information received therefrom. The method includes during the initial period, limiting an acceleration of said actuator from the zero speed to the deployment speed. The system has a control unit with a force fight controller and an acceleration limiter.