Hydrodynamic swing damper and tree handling vehicle incorporating the same

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.

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.

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.

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.