| 摘要 |
<p>An implement attachment in the form of, for example, a backhoe is mounted on the three-point hitch of a tractor having an internal hydraulic system which is incapable of preventing free upward swinging on the part of the hitch links. The implement itself includes a main frame attached to the hitch and a digging tool swingably mounted on the frame such that substantial resistance to digging by the tool generates a force which tends to lift the frame and the hitch links from the ground. This reaction is counteracted, however, by the application of a hold-down force against the frame at all times through a single-acting piston and cylinder assembly positioned between the tractor and the frame that is disposed in parallel flow relationship with the other hydraulically operated components of the implement such that increased efforts on the part of the digging tool to lift the frame when additional resistance is encountered automatically results in increased hold-down force applied by the piston and cylinder assembly. The hold-down piston and cylinder assembly is so sized that while being capable of exerting all counteractive force necessary to maintain the implement frame in a stable earth-working position during operation, the hitch links and implement can be raised to a transport position by the internal hydraulic system of the tractor without disconnecting the hold-down piston and cylinder assembly.</p> |
