Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D49/00—Tractors
  • B62D49/06—Tractors adapted for multi-purpose use
  • B62D49/0621—Tractors adapted for multi-purpose use comprising traction increasing arrangements, e.g. all-wheel traction devices, multiple-axle traction arrangements, auxiliary traction increasing devices
  • B62D49/0635—Tractors adapted for multi-purpose use comprising traction increasing arrangements, e.g. all-wheel traction devices, multiple-axle traction arrangements, auxiliary traction increasing devices using additional ground engaging means, e.g. endless tracks
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D55/00—Endless track vehicles
  • B62D55/08—Endless track units; Parts thereof
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D55/00—Endless track vehicles
  • B62D55/08—Endless track units; Parts thereof
  • B62D55/30—Track-tensioning means
  • B62D55/305—Track-tensioning means acting on pivotably mounted idlers

Definitions

• the invention relates to apparatus for ten- sioning track positioned about wheels in a continuous track assembly. More particularly, the invention relates to first and second wheels associated with first and second elements which are pivotally movable to adjust track tension by changing position of the wheels.
• a continuous track assembly is used on a work vehicle to provide increased traction.
• the track assembly generally includes wheels about which a track is positioned. It is desirable that the track conform to uneven terrain during operation of the vehicle and not penetrate the terrain surface. This provides maximum tractive effort and does not seriously disturb ground conditions.
• the present invention is directed to over ⁇ coming one or more of the problems as set forth above.
• a work vehicle has a frame and a first element connected to and pivotally movable relative to the frame.
• a second element is pivotally connected to the first element.
• Each of the first and second elements has a rotatable wheel about which a track is positioned.
• Power means is
• OMPI provided for rotating the first wheel for driving the track.
• Preselected tension in the track is maintained by means for controllably moving the second element relative to the first wheel.
• the wheels are pivotally movable together to adjust to changes in the terrain.
• Tension in the track is maintained through movement of the wheel associated with the second element inside of, and against, the track.
• the drawing is a diagrammatic side view in partial cutaway of one embodiment of the present in ⁇ vention.
• a work vehicle 10 has a continuous track assembly 12 and a frame 14.
• the frame has an axis 16 about which the continuous track assembly is oriented on the vehicle, as will be dis ⁇ cussed.
• the continuous track assembly includes first and second elements 18,20 having first and second wheels 22,24, respectively, connected thereto.
• the wheels each have an axis 26,28 about which they are rotatable on their respective elements.
• a track 30 is positioned about and in contact with both the first and second wheels and has a tension relative to said wheels.
• said wheels are represented by tires, such as of the pneumatic * type, which are enveloped by a flexible belt having individual shoes which represents the track. It should be understood that the wheels and track can be of other configurations as is known in the art without departing from the invention.
• the first element 18 is connected to the frame 14 and pivotally movable relative to the frame about the axis 16 of the frame.
• the second element 20 is pivotally connected to the first element and pivotally movable relative to said first element about its pivotal con ⁇ nection thereto between first and second positions 32,34.
• the first and second wheels are, as a result, movable one relative to the other and at said first position 32 of the second element, the axes 26,28 of said wheels are spaced a first preselected distance one from the other and at said second position 34 said axes are spaced a second preselected different distance one from the other.
• the distance between the axes is controllably determined to adjust or maintain tension in the track 30, as will be further explained.
• the power means 36 for rotating the first wheel 22 for driving the track 30.
• the power means can be, for example, a hydraulic motor and bevel gear drive 38 as shown or any other source of rotational motion, such as a hydrostatic drive where a hydraulic motor placed at the first wheel and powered through lines entering the first element at the frame axis 16 directly drives the first wheel.
• the orientation of the gear drive results in an axis of rotation 40 of the power means substan ⁇ tially the same as or aligned with the axis 16 of the frame.
• a first sprocket 42 is also connected to the gear drive and rotatable about its axis in response to rotational output of the hydraulic motor.
• Driving means 44 shown as a chain 46, the first sprocket and a second sprocket 48, transfers the rotational motion initiated about the axis of rotation by the motor to the first wheel.
• the second sprocket 48 is connected to and rotates with the first wheel.
• the chain is positioned about and in engagement with both sprockets to transfer the rotational motion and drive the first wheel.
• the work vehicle 10 also has means 50 for co trollably moving the second element 20 relative to the first element 18 or wheel 22 for controllably main ⁇ taining a preselected tension in the track 30 relative to the wheels 22,24.
• the track assembly 12 has a hydraulic cylinder 52 connected at a first end 53 to the first element and at a second end 54 to the second element.
• the cylinder as a portion of the track tensioning means, can be used to adjust or maintain track tension in that it is positioned at a location sufficient for pivotally moving the first and second elements between their first and second positions 32,34.
• the track tensioning means 50 also includes a hydraulic circuit 55 to control operation of the hy- draulic cylinder.
• the circuit shown is of a configur ⁇ ation sufficient for automatically, controllably main ⁇ taining a preselected fluid pressure to the hydraulic cylinder in response to the amount of tension of the track 30 relative to the first and second wheels 22,24.
• the cylinder is connected by the circuit to a high pressure fluid source 56.
• the circuit consists of a supply line 58 connecting the fluid source to a first end fluid chamber 60 of the cylinder.
• a check valve 62 in the supply line 58 controls flow in a single direc- tion from the fluid source to the cylinder.
• a second end fluid chamber 66 is connected to a return line 68.
• a relief valve 70 connects to the supply line between the check valve and the cylinder and to the return line.
• a two position dump valve 72 can be connected between the lines to exhaust fluid from the supply line and the first fluid chamber to a tank 74 for retracting the cylinder and collapsing the track.
• the track tensioning means 50 or circuit 54 can also be of other configurations as is known in the art. It should be understood that the track assembly 12 and particularly the first and second elements 18,20 and power and driving means 36 can be of other configurations as is known in the art without departing from the invention.
• the second element 20 In initiating or maintaining desired tension in the track 30, the second element 20 is pivotally moved relative to the first element 18 to position the first wheel axis 26 a preselected ' distance from the second wheel axis 28. In this manner, the first and second wheels 22,24 are- urged against the track 30 for the desired tension. Therefore, the tendency of the track under certain conditions to loosen and to slip or jump from the wheels, or to tighten and cause damage to the track assembly 12, is substantially overcome.
• the hy ⁇ draulic motor and bevel gear drive 38 rotate the first wheel 22 through the chain drive mechanism 44.
• the driven wheel engages the track 30 to propel the vehicle 10.
• the track assembly 12 components tend to conform to the terrain during movement of the vehicle 10 owing to the first and second elements 18,20 moving pivotally as a unit in response to uneven terrain conditions.
• the track 30 also conforms to the terrain and to foreign objects located between the track and one of the wheels. Therefore, the pathway about the wheels 22,24 through which the track passes also changes. The result is a change in track tension relative to the wheels.
• track tension is controllably maintained by the hydraulic cylinder in response to relative movement of elements in the track assembly 12.
• fluid passes from the fluid source 56, through the supply line 58, and to the first end chamber 60. This tends to extend the cylinder and pivotally, outwardly move the first and second elements 18,20 relative to one another. Therefore, the outer surfaces of the wheels 22,24 continuously urge against the track 30 to create tension on the track. The tension is determined by the pressure of the fluid passing to the chamber 60 and by the relief valve 70.
• biasing means 76 shown as a spring, at a pre- ' selected magnitude. This moves the relief valve 70. to the open position, fluid is exhausted through the return line 68 to the tank 76, and track tension becomes less as the second element 20 moves, for example, from the second position 34 toward the first position 32.
• a constant preselected range of fluid pressure in the hydraulic circuit and predetermined expansion of the track relative to said pressure range serve to controllably maintain the tension of the track relative to the wheels 22 and 24.
• the hydraulic circuit 55 and cylinder 52 in effect, auto- matically move the second element 20 relative to the first element 18 in response to a change in the pre ⁇ selected tension in the track 30 for automatically, controllably maintaining the preselected tension.
• the continuous track assembly 12 substantially prevents problems associated with track slippage relative to the wheels or with reduced traction.
• more tension can be created in the track by raising the pressure relief setting of the relief valve 70. Such action will not increase the power required to drive the track assembly 12 (up to, for example, bearing overload) , but more power can be used.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Devices For Conveying Motion By Means Of Endless Flexible Members (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=22235774

Family Applications (1)

Country Status (4)

Cited By (4)

Citations (9)

• 1979
  • 1979-12-03 GB GB8106413A patent/GB2074959B/en not_active Expired
  • 1979-12-03 WO PCT/US1979/001038 patent/WO1981001395A1/en unknown
  • 1979-12-03 JP JP80500188A patent/JPS56501481A/ja active Pending
• 1981
  • 1981-05-10 SE SE8102485A patent/SE8102485L/ unknown

Patent Citations (9)

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