Hydrodynamic swing damper and tree handling vehicle incorporating the same

• US 5,026,248 A
• Filed: 08/04/1989
• Issued: 06/25/1991
• Est. Priority Date: 03/17/1989
• Status: Expired due to Term

• Current Assignee: Quadco Equipment Inc. (Komatsu Ltd.)
• Original Assignee: Logging Development Corporation
• Inventors: Hamilton, Douglas D.
• Primary Examiner(s): Spar, Robert J.
• Assistant Examiner(s): Underwood, Donald W.
• Application Number:
  US07/389,687
• Time in Patent Office: 690 Days
• Field of Search: 414/729, 414/738, 414/739, 294/119.4, 188/279, 188/300, 188/319, 188/282, 188/322.15, 188/302, 188/310
• US Class Current: 414/729
• CPC Class Codes: A01G 23/083 Feller-delimbers
• CPC Class Codes: B66C 3/005 Grab supports, e.g. articulations; Oscillation dampers; Orientation B66C3/16 takes precedence

Abstract

A swing damper and a swing damper in one or more pivot joints, suspending a work tool such as a grapple from a boom. The swing damper is a hydraulic pivot joint where pivoting at the joint causes movement of a piston, in a closed chamber, that separates the chamber into first and second inter-related variable volume chamber portions. Upon movement of the piston, fluid is forced through a restricted opening from one chamber portion to the other with the amount of restriction determining the degree of damping. The piston is moved linearly in the chamber by a motion translating means operatively interconnecting the pivot shaft and piston. The motion translating means preferably is a screw thread on the shaft mating with a threaded aperture in the piston. Rods pass through the piston preventing it from rotating in the chamber.

Claims

1. Improvements in dampening oscillation of a work tool suspended from a boom comprising at least one hydraulically damped pivot joint connecting said work tool to said boom, said pivot joint including a housing fixed to one or the other of the boom and work tool suspended therefrom;

a chamber in said housing, a piston reciprocally mounted in said chamber and separating the same into first and second inter-related variable volume chamber portions;

a shaft pivotally mounted on said housing and connected to the other of said boom and work tool, motion translating means comprising a screw thread of selected pitch on a portion of said shaft in said chamber and internal thread means on an aperture through said piston mating with said threaded portion of said shaft whereby said piston moves linearly along the shaft in response to rotation of such shaft in response to pivotal relative movement at said joint between the boom and the work tool;

means preventing rotation of said piston;

a fluid flow passage from one to the other of said first and second chamber portions and means restricting the rate of flow through said passage means.

2. The improvement as defined in claim 1, including means to selectively adjust the flow rate capacity through said passage means.

3. The improvement as defined in claim 1, wherein said piston is circular in outline configuration and wherein said rotation preventing means comprises at least one rod fixed to the housing and projecting through a hole in said piston, said at least one rod being at a position offset from and parallel to said shaft.

9. A swing damping means as defined in claim 1 wherein said fluid flow passage means comprises at least one hole through said piston.

10. A swing damping means as defined in claim 1 wherein said fluid flow passage means comprises a channel through said shaft, extending from one of said chamber portions to the other.

11. A swing damping device as defined in claim 10 including means selectively to vary the rate of flow of a selected fluid through said channel.

12. A swing damping means as defined in claim 11 including a remotely operable shut-off valve selectively to preclude flow of fluids through said channel.

13. A swing damping means as defined in claim 9 including at least one pressure relief valve in the piston, limiting maximum pressure in at least one of said chamber portions and discharging into the other.

14. A swing damping means as defined in claim 1 wherein said fluid flow passage means comprises pre-determined leakage between at least one of the piston and wall of the cylindrical chamber and the threaded engagement of the piston with the shaft.

4. A tree handling apparatus comprising:

(a) a mobile vehicle having a boom mounted thereon;

(b) a work tool; and

(c) pivot means connecting said work tool to said boom, said pivot means including a hydraulically damped pivot joint restraining oscillatory movement of the work tool resulting from movement of the vehicle and/or boom, said pivot joint including a housing secured to one or the other of said boom and work tool and a shaft journalled on said housing and secured to the other, said housing having a chamber with said shaft projecting thereinto, an external screw thread on said shaft in said chamber, a piston threaded on said shaft and separating said chamber into first and second interrelated variable volume chamber portions, means preventing rotating of said piston in said chamber whereby relative movement of said housing and shaft cause said piston to move linearly along said shaft, fluid flow passage means within said housing providing liquid flow communication from one to the other of said first and second chamber portions and means in said passage means restricting the flow rate therethrough whereby relative movement of said shaft and housing is dampened.

5. Tree handling apparatus as defined in claim 4 including a pair of said pivot joints interconnected in the form of a universal joint with the pivot axis of one pivot joint being substantially at right angles to the pivot axis of the other.

6. A device for use in pivotally interconnecting respectively first and second members comprising:

a housing securable to said member and having a fluid confining chamber therein;

a piston reciprocally mounted in said chamber separating such chamber into first and second interrelated variable volumn chamber portions, said piston having a threaded aperture extending therethrough along the axis thereof;

a fluid flow path from one to the other of said first and second chamber portions;

fluid flow control means in said flow path allowing a predetermined rate of flow of a selected fluid from one chamber portion to the other;

a shaft pivotally mounted on said housing and securable to said second member; and

motion translating means comprising external threads on said shaft mating with said threaded aperture axially through said piston and means preventing rotation of said piston about its axis whereby relative movement of said first and second members, through pivoting about their pivotal interconnection, causes linear movement of the piston in a direction along its axis forcing fluid from one to another of said first and second chamber portions, said flow control means restricting said fluid flow whereby relative movement of said first and second members is dampened.

7. A swing damping means for pivotally interconnecting respectively first and second members such as, for example, a boom and a work tool suspended therefrom comprising:

(a) a cylindrical housing rigidly securable to said first member;

(b) end caps on said housing providing a fluid confining chamber therebetween, at least one of said end caps being detachably secured to said housing;

(c) a shaft extending through said chamber and journalled on said end caps, said shaft having opposite end portions, extending beyond said end caps that are securable to said second member, said shaft having a threaded portion disposed between said end caps and concentric with the longitudinal axis of the housing, said shaft providing said pivotal interconnection of said first and second members;

(d) a cylindrical piston threaded on said shaft and disposed in sealing engagement with said cylindrical housing separating said chamber into first and second inter-related variable in volume chamber portions respectively on opposite sides of the piston;

(e) means preventing rotation of said piston whereby relative movement of said first and second members causes said piston to move axially along said threaded shaft; and

(f) fluid flow passage means from one to the other of said chamber portions including means therein, allowing a predetermined rate of flow of a selected liquid from one chamber portion to the other to dampen relative movement of said first and second member.

8. a swing damping means for use in pivotally interconnecting a first and second member, for example, a boom and work tool comprising:

(a) a cylindrical housing having a cylindrical chamber closed at respective opposite ends by end caps;

(b) a shaft extending through said chamber and journalled for rotation on said end caps, said shaft being located on the longitudinal axis of said chamber and extending beyond and carried by said end caps, said shaft having a threaded portion in said chamber between said end caps;

(c) a cylindrical piston, threaded on said shaft and sealed against the cylindrical chamber separating the same into first and second inter-related variable volume chamber portions;

(d) means connecting said piston to the housing preventing rotation of the piston and allowing linear movement only of the piston in a direction along the axis of the chamber;

(e) fluid flow passage means including means restricting the rate of flow of fluid from one to the other of said chamber portions respectively on opposite sides of the piston; and

(f) means rigidly securing said housing and shaft to said respective first and second members, relative movement of said first and second members causing said piston to move axially in said housing against the resistance to fluid flow thereby dampening relative movement of said first and second members.

15. Improvements in dampening swinging movement of a work tool suspended from a movably mounted boom comprising at least one hydraulically damped pivot joint connecting said work tool to said boom, said pivot joint including a housing secured to one of a frame mounting structure of said work tool and said boom and having a chamber therein, a piston reciprocally mounted in said chamber and separating the same into inter-related variable volume fluid confining chamber portions, a shaft extending axially through said piston and chamber and secured to the other of said boom and frame mounting structure of the work tool, means preventing rotation of said piston relative to said housing, gear thread means on said shaft mating with a threaded bore axially through said piston whereby relative movement of said work tool and boom causes said piston to move linearly along the shaft forcing fluid in one of said chamber portions to the other of said chamber portions and fluid flow passage means including flow control means therein permitting restricted flow of the fluid from one to the other of said chamber portions and thereby dampening relative movement of said work tool and boom.

16. A swing damping means as defined in claim 15 wherein said fluid flow passage means comprises at least one hole through said piston.

17. A swing damping means as defined in claim 15 wherein said fluid flow passage means comprises a channel through said shaft, extending from one of said chamber portions to the other.

18. A swing damping device as defined in claim 17 including means selectively to vary the rate of flow of a selected fluid through said channel.

19. A swing damping means as defined in claim 17 including a remotely operable shut-off valve selectively to preclude flow of fluid through said channel.

20. A swing damping means as defined in claim 15 including at least one pressure relief valve in the piston, limiting maximum pressure in at least one of said chamber portions and discharging into the other.

21. A swing damping means as defined in claim 15 wherein said fluid flow passage means comprises pre-determined leakage between at least one of the piston and wall of the cylindrical chamber and the threaded engagement of the piston with the shaft.