In the operation of hydraulic equipment and, particularly, earth moving and excavating apparatus, the operator is faced with a peculiar problem. When he moves the operating handle of the valve which controls the flow of pressure fluid to the cylinder being operated, the valve suddenly opens in the intermediate part of the handle stroke. This causes the fluid to flow to the cylinder suddenly and to begin operation of the apparatus with a jerk. Furthermore, if he tries to hold the handle with the valve slightly open to permit slow movement of the apparatus, or even for the purpose of jogging the apparatus, he is faced with the fact that the vehicle on which the apparatus is mounted may be traveling over rough terrain. Similarly, even if the vehicle is in a fixed position adjacent an excavation, for instance, the erratic forces to which the apparatus is being subjected as it moves through earth and rock causes the operator to be so moved about on the vehicle, so that it is difficult for him to maintain the handle in a fixed position relative to the valve. The result of this motion of the operator in the vehicle and the difficulty in holding the handle fixed relative to the valve, is that the operation of the cylinder and of the excavation apparatus is erratic, so that not only is the operation carried on in less than a smooth manner, but the entire hydraulic system is being subjected to force and pressure changes that cause more wear than is necessary. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the invention to provide a control system which permits an operator to regulate a hydraulic cylinder to operate smoothly despite jarring of the vehicle in which he is seated.
A further object of the present invention is the provision of a control apparatus for a hydraulic actuator that eliminates erratic behavior of the apparatus for reasons not connected with the work being performed.
It is another object of the instant invention to provide a control system for providing an operator with a strong indication of the point in valve motion when flow of pressure fluid begins to take place to a hydraulically operated apparatus.
A still further object of the invention is the provision of a control system including apparatus to permit an operator to control hydraulically-actuated apparatus smoothly despite the movement of the vehicle to which the apparatus is attached moving over rough terrain.
It is a further object of the invention to provide a control system associated with hydraulically-actuated apparatus permitting an operator to select and maintain the flow of fluid to a cylinder at a selected amount.
It is a still further object of the present invention to provide a control system including sensing apparatus that can readily be applied to pre-existing equipment.
Another object of the invention is the provision of a control system including sensing apparatus that is rugged in construction, relatively simple to manufacture, and which is capable of a long life of useful service with a minimum of maintenance even in dusty conditions.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.