Hydraulic system for backhoe

#This invention relates generally to mobile machinery and, more particularly, to earthmoving and digging machinery.

#Mobile machinery, i.e., machinery capable of self=propelled movement across a floor or earthen surface, is available in a wide variety of configurations. Each is designed for a particular purpose or for a few related purposes such as material handling or earthmoving and digging. Machines of the latter type, often referred as "construction machinery," include backhoes, front end loaders and "hybrids," loader-backhoes.

#Advantageously, the working implements of backhoes, front end loaders and hybrid machines are powered by a hydraulic system controlled by lever-like handles mounted in the operator's compartment. Such handles actuate hydraulic valves which operate hydraulic cylinders and, frequently, rotary motors to power auxiliary equipment.

#FIG. 1 is a representative view of a loader-backhoe machine.

#FIG. 2 is a representative side elevation view of the backhoe portion of the machine of FIG. 1 showing such portion in an extended position.

#FIG. 3 is a representative side elevation view of the backhoe portion of FIG. 2 showing such portion in a partially retracted position.

#Referring to FIGS. 1 and 4, the improved hydraulic system 10 is disclosed in connection with a machine 11 embodied as an exemplary loader-backhoe 13. The loader-backhoe 13 of FIG. 1 includes a chassis having an engine 15, an operator's cab 17, and a first implement 19, e.g., a loader bucket 21 mounted on pivoting arms 23. The positions of the bucket 21 and the arms 23 are controlled by a first valve section 25 in the cab 17.

#The machine 11 also has a second implement 27, e.g., a rear-mounted backhoe 29 with a boom 31, a dipper 33 and a bucket 35 attached to the end of the dipper 33. The dipper 33 has a telescoping extensible portion 37 configured and arranged so that such portion 37 may be extended toward and away from the joint 39. From FIG. 1, it is apparent that when the portion 37 is extended to the rear of the machine 11, the "reach" of the backhoe 13 (horizontally, vertically as into a trench, or a combination thereof) is significantly improved.

#It is to be appreciated that the backhoe 29 pivots at the joint 39 between the boom 31 and the dipper 33 and at the joint 41 between the dipper 33 and the bucket 35. The backhoe 29 also pivots left-and-right (in the drawing, into and out of the paper) about the joint 43. Because of such configuration, the bucket 35 has what is known as "three axes of movement," i.e., it can be moved in any direction.