Tensioning device for track apparatus

• US 6,543,861 B1
• Filed: 07/28/2000
• Issued: 04/08/2003
• Est. Priority Date: 07/28/2000
• Status: Expired due to Term

• Current Assignee: ATI Incorporated (CNH Industrial N.V.)
• Original Assignee: Agtracks Inc (CNH Industrial N.V.)
• Inventors: Reshad, Jamsheed, Kahle, Glenn W., Juncker, David L.
• Primary Examiner(s): Stormer, Russell D.
• Application Number:
  US09/627,861
• Time in Patent Office: 984 Days
• Field of Search: 305/135, 305/143, 305/145, 305/146, 305/147, 305/148, 267/113, 267/118, 267/124, 267/64.11
• US Class Current: 305/143
• CPC Class Codes: B62D 55/04 with tracks and alternative ground wheels, e.g. changeable from endless track vehicle into wheeled vehicle and vice versa for multi-purpose tractors B62D49/0635
• CPC Class Codes: B62D 55/30 Track-tensioning means
• CPC Class Codes: B62D 55/305 acting on pivotably mounted idlers

Abstract

A tensioning device is provided for maintaining the tension on a continuous flexible track of a track apparatus. The track apparatus includes an idler wheel which engages the flexible track and which is movable between a first non-deflected position and a second deflected position. A dampening mechanism extends between an idler axle which supports the idler wheel and the frame of the track apparatus in order to exert a force on the idler axle to urge the idler wheel towards the non-deflected position. The dampening mechanism progressively increases the force on the idler axle as the idler wheel moves towards the deflected position.

Claims

1. A tensioning device for maintaining tension on a continuous flexible track of a track apparatus, the track apparatus including a frame, a drive wheel structure rotatably mounted with respect to the frame, and an idler assembly having an idler wheel engaging the track, the idler assembly being moveable with respect to the frame, the tensioning device comprising:

a main-cylinder housing interconnected to one of the frame and and the idler assembly, the housing extending along an axis and defining a main chamber therein;

a main piston having a first end operatively connected to the other of the frame and the idler assembly and a second end slidably received within the chamber, the piston movable between a retracted position and an extended position;

a primary dampening structure for resisting movement of the piston toward the retracted position for a first predetermined axial length; and

a secondary dampening structure for resisting movement of the piston toward the retracted position for a further axial length beyond the first predetermined axial length, the secondary dampening structure resisting movement of the piston independent of the primary dampening structure.

2. The tensioning device of claim 1 wherein the primary dampening structure includes:

a primary cylinder extending along an axis and defining a primary chamber therein; and

a primary piston slidably received in the primary cylinder and movable axially between a first and second position, the primary piston dividing the primary chamber into a first portion for receiving a pressurized gas and a second portion.

3. The tensioning device of claim 2 further comprising:

a hydraulic fluid conduit interconnecting the main chamber and the second portion of the primary chamber; and

a hydraulic fluid disposed within the second portion of the primary chamber, the main chamber, and the conduit therebetween.

4. The tensioning device of claim 3 wherein the secondary dampening structure includes:

a secondary cylinder extending along an axis and defining a secodary chamber therein; and

a secondary piston slidably received in the secondary cylinder and movable axially between a first and second position, the secondary piston dividing the secondary chamber into a first portion for receiving a pressurized gas and a second portion;

whereby the conduit interconnects the main chamber and the second portion of the secondary chamber and wherein the hydraulic fluid is disposed within the second portion of the secondary chamber.

5. The tensioning device of claim 4 wherein the pressure of the pressurized gas in the first portion of the secondary chamber is greater than the pressure of the pressurized gas in the first portion of the primary chamber.

6. The tensioning device of claim 2 wherein the primary cylinder includes an inner surface which defines the primary chamber therein.

7. The tensioning device of claim 6 further comprising a limiter extending from the inner surface of the primary cylinder, the limiter limiting movement of the primary piston within the primary chamber.

8. The tensioning device of claim 2 wherein the secondary dampening structure includes:

a secondary cylinder extending along an axis, defining a secondary chamber therein and having an input; and

a secondary piston slidably received in the secondary cylinder and movable axially between a first and second position, the secondary piston dividing the secondary chamber into a first portion for receiving a pressurized gas and a second portion of the primary chamber therein.

9. The tensioning device of claim 8 further comprising:

a manifold having an input, a first output operatively connected to the input of the primary cylinder, and a second input operatively connected to the input of the secondary cylinder;

a hydraulic fluid disposed within the conduit for travel between the main chamber, the second portion of the primary chamber and the second portion of the secondary chamber.

10. The tensioning device of claim 1 wherein the idler assembly includes:

an idler-axle support mounted with respect to the frame; and

an idler axle extending through the idler-axle support, the idler wheel being mounted on the idler axle and movable with the axle between a non-deflected position corresponding to the extended position of the main piston and deflected position corresponding to the retracted position of the main piston.

11. The tensioning device of claim 10 wherein the primary and secondary dampening structures operate to progressively increase resistance to movement of the idler wheel toward the deflected position as the idler wheel moves toward the deflected position.

12. The tensioning device of claim 10 wherein the idler-axle support is pivotably mounted to the frame.

13. The tensioning device for maintaining tension on a continuous flexible track of a track apparatus, the track apparatus including a frame, a drive wheel structure rotatably mounted with respect to the frame, and an idler assembly having an idler wheel engaging the track, the idler assembly being movable with respect to the frame, the tensioning device comprising:

a main-cylinder housing interconnected to one or the frame and the idler assembly, the housing extending along an axis and defining a main chamber therein;

a main piston having a first end operatively connected to the other of the frame and the idler assembly and a second end slidably received within the chamber, the piston movable between a retracted position and an extended position, the dampening mechanism mounted at a position remote from the housing and piston and progressively increasing the force on the second end as the position moves toward the retected poisition.

14. The tensioning device of claim 13 further comprising a conduit operatively connecting the dampening mechanism and the second end and wherein the dampening mechanism includes:

a primary cylinder extending along an axis and defining a primary chamber therein;

a primary piston slidably received in the primary cylinder and movable axially between a first and second position, the primary piston dividing the primary chamber into a first portion for receiving a pressurized gas and a second portion;

a secondary cylinder extending along an axis and defining a secondary chamber therein;

a secondary piston slidably received in the secondary cylinder and movable axially between a first and second position, the secondary piston dividing the secondary chamber into a first portion for receiving a pressurized gas and a second portion, the second portion of the primary chamber interconnected to the second portion of the secondary chamber and the main chamber by the conduit; and

a hydraulic fluid disposed within the conduit.

15. The tensioning device of claim 14 further comprising a first pressurized gas disposed within the first portion of the primary chamber for urging the pirmary piston toward the first position and a secondary pressurized gas disposed within the first portion of the secondary chamber for urging the secondary piston toward the first position.

16. The tensioning device of claim 15 wherein the pressure exerted by the second pressurized gas on the secondary piston is greater than the pressure exerted by the first pressurized gas on the primary piston.

17. The tensioning device of claim 14 wherein the primary cylinder includes an inner surface which defines the primary chamber therein.

18. The tensioning device of claim 17 further comprising a limiter extending from the inner surface of the primary cylinder, the limiter limiting movement of the primary piston within the primary chamber.

19. The tensioning device of claim 14 wherein the conduit includes:

a manifold having an input, a first output communicating with the second portion of the primary chamber, and a second output communicating with the second portion of the secondary chamber; and

a flow tube interconnecting the input of the manifold and the main chamber.

20. The tensioning device of claim 13 wherein the idler assembly includes:

a idler-axle support mounted with respect to the frame; and

an idler axle extending through the idler-axle support, the idler wheel being mounted on the idler axle and movable with the axle between a non-deflected position corresponding to the extended position of the main piston and a deflected position corresponding to the retracted position of the main piston.

21. The tensioning device of claim 20 wherein the idler-axle support is pivotably mounted to the frame.