Manual suspension locking of a skid steer vehicle having a sprung suspension

A skid steer vehicle comprising:

• a chassis having a left side and a right side;
• at least one loader arm pivotally coupled to the chassis to pivot about a substantially horizontal axis;
• at least one hydraulic cylinder coupled to the at least one loader arm to raise and lower the at least one loader arm with respect to the chassis;
• an engine coupled to the chassis;
• first and second variable displacement hydraulic pumps coupled to the engine to provide two separately controllable sources of hydraulic fluid under pressure;
• four non-steerable and ground-engaging wheels coupled to the chassis to drive the vehicle over the ground, wherein the wheels are disposed two on each side of the chassis in a fore-and-aft relation;
• two control arms, each of the two control arms pivotally coupled to and between the chassis and an associated forward wheel of the four wheels to permit the associated forward wheel to pivot in at least a vertical direction with respect to the chassis;
• at least two hydraulic motors for driving the four wheels wherein at least one motor is driven by fluid from the first pump and in turn drives the wheels on the left side of the chassis and at least another motor is driven by fluid from the second pump and in turn drives the wheels on the right side of the chassis;
• two hydraulic cylinders, each cylinder operably coupled to one of the two forward wheels of the four wheels to control at least the vertical position of said one of the two forward wheels with respect to the chassis;
• a set of manually-actuable operator controls including at least a first operator-actuable control configured to signal a desired wheel rotation, and at least a second operator-actuable control configured to signal a desired movement of the at least one loader arm;
• a manually-actuable operator input device configured to generate a signal indicative of a request for suspension locking;
• an electronic controller operably coupled to the set of manually-actuable operator controls, the manually-actuable operator input device, the first and second pumps, and the at least one hydraulic cylinder, to vary the displacement of the first and second pumps in response to manipulation of the first operator-actuable control, to fill the at least one hydraulic cylinder in response to manipulation of the second operator-actuable control, and to lock the two forward wheels in a vertical position with respect to the chassis in response to manipulation of the manually-actuable operator input device.

A method of manually locking the suspensions of a skid steer vehicle, the vehicle including:

• a chassis having a left side and a right side;
• at least one loader arm pivotally coupled to the chassis to pivot about a substantially horizontal axis;
• at least one hydraulic cylinder coupled to the at least one loader arm to raise and lower the at least one loader arm with respect to the chassis;
• an engine coupled to the chassis;
• first and second variable displacement hydraulic pumps coupled to the engine to provide two separately controllable sources of hydraulic fluid under pressure;
• four non-steerable and ground-engaging wheels coupled to the chassis to drive the vehicle over the ground, wherein the wheels are disposed two on each side of the chassis in a fore-and-aft relation;
• two control arms, each of the two control arms pivotally coupled to and between the chassis and an associated forward wheel of the four wheels to permit the associated forward wheel to pivot in at least a vertical direction with respect to the chassis;
• at least two hydraulic motors for driving the wheels wherein at least one motor is driven by fluid from the first pump and in turn drives the wheels on the left side of the chassis and at least another motor is driven by fluid from the second pump and in turn drives the wheels on the right side of the chassis;
• two hydraulic cylinders, each cylinder operably coupled to one of the two forward wheels of the four wheels to control at least the vertical position of said one of the two forward wheels with respect to the chassis;
• a set of manually-actuable operator controls including at least a first operator-actuable control configured to signal a desired wheel rotation, and at least a second operator-actuable control configured to signal a desired movement of the at least one loader arm;
• a manually-actuable operator input device configured to generate a signal indicative of a request for suspension locking;
• and
• an electronic controller operably coupled to the set of manually-actuable operator controls, the manually-actuable operator input device, the first and second pumps, and the at least one hydraulic cylinder to vary the displacement of the first and second pumps in response to manipulation of the first operator-actuable control, to fill the at least one hydraulic cylinder in response to manipulation of the second operator-actuable control, and to lock the two forward wheels in a vertical position with respect to the chassis in response to manipulation of the manually-actuable operator input device, the method comprising the steps of:
• manipulating the manually-actuable operator input device to generate a locking command indicative of a wheel locking request;
• receiving the locking command in the electronic controller;
• and
• locking the two forward wheels to prevent vertical motion of the two forward wheels with respect to the chassis in response to receipt of the locking command in the electronic controller.