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US 6,634,445 B2Granted
Skid steer vehicle having suspensions that are locked based on vehicle speed
AssigneeCase Corporation
InventorsPeter J. Dix, Hong-Chin Lin, Brian E. Felsing, Troy D. Bateman, Anthony J. Lamela, Daniel B. Shore
Life of this patent
Estimating the term…
Abstract
A skid steer vehicle includes a chassis mounted on four sprung suspensions that are controlled by an electronic controller. The controller monitors the speed of the vehicle and locks the suspensions when the vehicle falls below a predetermined speed.
Claims17
A skid steer vehicle comprising:
- a chassis having a left side and a right side;
- 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;
- four control arms pivotally coupled to the chassis and coupled to the four wheels to permit the wheels to pivot at least in 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;
- four hydraulic cylinders, each cylinder operably coupled to one of the wheels to control at least the vertical position of the wheels with respect to the chassis;
- a speed sensing means to provide a signal indicative of the speed of the vehicle over the ground;
- and
- an electronic controller coupled to the speed sensing means and to the hydraulic cylinders that is configured to lock the four wheels in a vertical position with respect to the chassis when the vehicle falls below a predetermined speed.
7 more elements
A skid steer vehicle comprising:
- a chassis having a left side and a right side;
- 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 to permit the associated forward wheel to pivot at least in 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 to control at least the vertical position of said one of the two forward wheels with respect to the chassis;
- a speed sensing means to provide a signal indicative of the speed of the vehicle over the ground;
- and
- an electronic controller coupled to the speed sensing means and to the hydraulic cylinders that is configured to lock the two forward wheels in a vertical position with respect to the chassis when the vehicle falls below a predetermined speed.
7 more elements
A method of controlling the suspensions of a skid steer vehicle, the vehicle including:
- a chassis having a left side and a right side;
- 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 to permit the associated forward wheel to pivot at least in 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 to control at least the vertical position of said one of the two forward wheels with respect to the chassis;
- a speed sensing means to provide a signal indicative of the speed of the vehicle over the ground;
- and
- an electronic controller coupled to the speed sensing means and to the hydraulic cylinders that is configured to lock the two forward wheels in a vertical position with respect to the chassis when the vehicle falls below a predetermined speed, the method comprising the steps of:
- reading the signal indicative of the speed of the vehicle;
- comparing the signal indicative of the speed of the vehicle with a value indicative of a predetermined speed;
- locking the two forward wheels of the four wheels to prevent vertical motion of the two wheels with respect to the chassis when the step of comparing indicates that the vehicle is traveling slower than the predetermined speed;
- and
- unlocking the two forward wheels to permit vertical motion of the two wheels with respect to the chassis when the step of comparing indicates that the vehicle is traveling above the predetermined speed.
12 more elements
Dependencies are inferred from the claim text.