초록 ▼

A prime mover (A) has an arm assembly (B) pivotally connected thereto. A cutting assembly (C) is operatively connected with the arm assembly to be positioned thereby. The arm assembly is connected to the tractor to pivot about both vertical and horizontal axes such that the cutting means is position

A prime mover (A) has an arm assembly (B) pivotally connected thereto. A cutting assembly (C) is operatively connected with the arm assembly to be positioned thereby. The arm assembly is connected to the tractor to pivot about both vertical and horizontal axes such that the cutting means is positionable fore-and-aft as well as up and down. A hydraulic control circuit (D) controls the position of the arm assembly. The control circuit includes a first through-rod-type hydraulic cylinder (60) which includes a piston (62) slidably disposed therein to divide the cylinder into two equidiameter chambers (64, 66). A through-rod (68) is connected with the piston and extends through both chambers of the cyylinder. The hydraulic cylinder and the piston rod each have the same diameter in both chambers such that as the piston moves, one of the chambers draws the same amount of fluid as the other chamber discharges. A unidirectional pressure relief valve (70) connects the two chambers to allow fluid to flow from one chamber to the other when the pressure differential therebetween exceeds a first preselected pressure, but blocks fluid flow in the opposite direction. This enables the arm assembly to break away in one direction. Additional through-rod-type hydraulic cylinders (80, 90) control the position of arms within the arm assembly and the position of the cutting apparatus. Additional one-way pressure relief valves (84, 94) are connected with the other hydraulic cylinders to allow the arm assembly and cutting assembly to break away.

대표청구항 ▼

A mobile cutting apparatus comprising: (a) a prime mover; (b) an arm assembly operatively connected with the prime mover such that the arm assembly undergoes rotational movement relative to the prime mover; (c) a cutting assembly operatively connected with the other end of the arm assembly; (d) a hy

A mobile cutting apparatus comprising: (a) a prime mover; (b) an arm assembly operatively connected with the prime mover such that the arm assembly undergoes rotational movement relative to the prime mover; (c) a cutting assembly operatively connected with the other end of the arm assembly; (d) a hydraulic breakaway circuit including: (i) a first through-rod-type hydraulic cylinder operatively connected with the arm assembly for controlling a rotational position of the arm assembly relative to the prime mover, the first cylinder including a cylinder housing, a piston slidably received within the cylinder housing dividing it into first and second chambers such that increasing the pressure in one chamber relative to the pressure in the other chamber causes the piston to move, and a through-rod extending from one end of the housing, through and fixedly attached to the piston, and through the other end of the housing, the rod having the same outer diameter in both the first and second chambers and the housing having the same inner diameter in both the first and second chambers such that the amount of fluid displaced from one of the chambers as the piston moves is the same as the amount of fluid required to maintain the other chamber filled; (ii) a hydraulic fluid control valve for controlling the relative pressure in the first and second chambers of the first hydraulic cylinder, the first hydraulic control valve having a first port in fluid connection with the first chamber and a second port in fluid communication with the second chamber; (iii) a first one-way, relief valve operatively connected between the first and second chambers for allowing fluid to flow from the first chamber to the second chamber when the pressure in the first chamber exceeds the pressure in the second chamber by a first preselected pressure, the first pressure relief valve prohibiting the flow of hydraulic fluid from the second chamber to the first chamber therethrough, whereby in response to the cutting assembly contacting a relatively immovable object which tends to cause the arm assembly to rotate in a first direction until the pressure differential exceeds the first preselected pressure and the first pressure relief valve permits fluid to flow between the hydraulic cylinder chambers allowing the arm assembly to rotate; (iv) a fluid reservoir; and, (v) a hydraulic fluid pump for pumping hydraulic fluid from the hydraulic fluid reservoir to the first hydraulic valve.