Assist assembly for cab structure

Claim 1

In a cab structure for an earth-working machine, said cab structure having the shape of an inverted open box with one edge thereof rotatably connected to a frame portion of said earth-working machine for permitting rotational movement of said cab structure about a horizontal axis that is transverse to the longitudinal axis of said machine, said cab structure being rotatable from a first stop position where its longitudinal axis is substantially parallel to the longitudinal axis of said machine to a second stop position where its longitudinal axis is substantially perpendicular to the longitudinal axis of said machine, the improvement comprising: an assist assembly for reducing the work required by an operator in rotating said cab structure from its first stop position to its second stop position or from its second stop position to its first stop position, said assist assembly including a bellcrank member rotatably connected to a support means on said machine frame portion, a transmission linkage pivotally attached at one of its ends to an upper end of said bellcrank member and having its opposite end pivotally attached to said cab structure at a point radially outward from said horizontal axis, an extensible and retractable actuator constantly biased toward an extended position, said actuator pivotally connected at one end to a support means on said machine frame portion and having its opposite end pivotally connected to an opposite lower end of said bellcrank member; the center of gravity for said cab structure moving through a point which is in direct vertical alignment with said horizontal axis when said cab structure is rotated from its first stop position to its second stop position or from its second stop position to its first stop position, said actuator applying a constant force on said bellcrank member that urges said bellcrank member to rotate in a first direction, the force from said actuator being transferred to said transmission linkage by said bellcrank member for providing mechanical assistance in rotating said cab structure until its center of gravity coincides with said point of vertical alignment with said horizontal axis, and said cab structure exerting a greater opposite force on said bellcrank member for rotating said bellcrank member in a direction opposite to said first direction when the center of gravity of said cab structure moves beyond said point of vertical alignment whereby said bellcrank member reverses the direction of stroke of said actuator and said actuator dampens or retards the rotational movement of said cab structure until it reaches a stop position.