A toe jack to attach to machines
A machine toe jack for mounting on a machine body, the toe jack having an extensible leg projectable from a hollow toe jack housing and attached to the machine body along the length of the housing. A piston cooperating in a cylinder in the extensible leg extends the leg from the housing. A hydraulic fluid reservoir is formed in the extensible leg in an annular space surrounding the cylinder. A valve block is coextensive with the extensible leg at the foot of the leg and contains the valves and pumping piston for the toe jack. Valving in the valve block permits manual extension and retraction of the extensible leg.
1. An extensible toe jack comprising:
a piston hydraulically operable in a cylinder;
a hydraulic fluid reservoir surrounding the cylinder along a substantial portion of its length;
a housing connected to the piston;
a valve block coextensive with the reservoir and at the base of the cylinder, said valve block fitting telescopically within the housing and comprising at least one hydraulic conduit therein in fluid communication between the reservoir andcylinder and having at least one check valve in the conduit, said valve block further comprising means for accessing the check valve through the exterior of the valve block, said accessing means being essentially flush with the exterior surface of thevalve block so as to permit substantially all of the valve block to be recessed telescopically into the housing so as to permit the housing to slidably cover the valve block when the piston is fully retracted into the cylinder; and
hydraulic fluid pumping means for pumping fluid from the reservoir to the cylinder.
2. An extensible toe jack comprising:
a piston hydraulically operable in a elongated cylinder;
a hydraulic fluid reservoir formed by a space between the cylinder and a wall of an extensible leg of the toe jack;
a housing connected to the piston;
a valve block coextensive with the extensible leg and at the base of the cylinder, said valve block fitting telescopically within the housing and comprising first hydraulic fluid communication means having first and second check valves thereinfor unidirectionally conducting fluid from the reservoir to the cylinder, said first hydraulic fluid communication means further comprising first and second plugs, said plugs being essentially flush with the external surface of the valve block so as topermit the extensible leg and substantially all of the valve block to be recessed telescopically into the housing when the piston is fully retracted, said plugs also having means adapted to receive a tool for removal of the plugs to provide access to thefirst and second check valves, said valve block further comprising second hydraulic fluid communication means operable between the cylinder and the reservoir having a manually controlled valve interposed therein; and
hydraulic fluid pumping means in communication with the first fluid communication means and between the first and second check valves.
1. Field of the Invention
The present invention relates to toe jacks which are mountable on a machine body and are useful for loading, removal, and/or leveling of the machine body.
2. The Prior Art
Currently there is a plethora of machine jacks available on the market ranging from simple mechanical toe jacks to sophisticated hydraulic units and are either demountable or are permanently mounted on the machine body.
One prior art machine toe jack, in particular, is attachable to a machine body only along a relatively short distance of the mid-section of the toe jack. An enlarged hydraulic fluid reservoir precludes snug engagement of the machine toe jack to the machinebody, and brackets must be used to bridge the resultant gap at the mid-section of the toe jack. Accordingly, the toe jack is attached to the machine body in a relatively insecure manner, particularly since attachment at the hydraulic fluid reservoir itself isnot possible. The reservoir also occupies a segment of the toe jack body which would otherwise be occupied, to some extent, by the extensible leg of the toe jack resulting, therefore, in a shorter extensibility of the toe jack.
With the valving mechanism and hydraulic fluid pumping apparatus of the toe jack located on top of the reservoir, the working level of the pump is elevated and is continually changing during operation of the toe jack. The constantly changing elevationof the working level is inconvenient and subjects to toe jack attachment point to undue stresses when the machine body tends to wobble.
A further problem arises from the upper hydraulic fluid reservoir because leaks, when they occur, result in hydraulic fluid staining a substantial portion of the length of the toe jack and thus serving to collect dust and debris on the toe jack.
Generally, manual extension of prior machine skates is possible only to a limited extent. Lowering of the extensible leg of the toe jack to contact with the ground so as to support a machine is, therefore, possible only through operation of the pumpingmechanism. This is both tedious and inconvenient, particularly if the extensible leg must be extended a considerable distance before it contacts the ground surface.
The present invention is a machine toe jack for mounting upon movable bodies such as machine bodies for facile raising, lowering, and leveling of the movable bodies. The toe jack is securely attachable to a machine body. Snug securement is possible sincethe hydraulic fluid reservoir is an integral part of the extensible leg and is formed in the annular space surrounding the toe jack cylinder. An elongated piston cooperates in the cylinder and is attached to a housing which completely enclosed theextensible leg upon retraction. A valve block coextensive with the extensible leg and at the base thereof contains the hydraulic fluid valving and pumping mechanisms. Access to all of the hydraulic fluid valving and pumping apparatus is easilyavailable from the external periphery of the valve block.
Facile manual extension and retraction are possible since the valving mechanism is located below the hydraulic fluid reservoir and the toe jack cylinder easily permitting transfer of hydraulic fluid from one to the other without operation of thepumping mechanism. Additionally, leaks, if they occur, stain only a small portion of the base of the toe jack and not the entire length thereof.
Not only does the housing serve to protect the toe jack apparatus during transit but also presents a uniform profile since the cross-sectional area of the toe jack is uniform along its entire length.
It is, therefore, a primary object of this invention to provide improvements in machine toe jacks.
It is another object of this invention to provide a machine toe jack wherein a substantial portion of the operating mechanism of the toe jack is retractable within a protective housing.
It is a further object of this invention to provide a machine toe jack wherein the operating level of the hydraulic pumping mechanism remains constant at ground level.
Another object of this invention is to provide a toe jack with an extensible leg that is manually extensible and retractable.
Another object of this invention is to provide a hydraulic toe jack with a hydraulic valve block wherein all hydraulic fluid control devices are readily accessible from the external periphery of the valve block.
These and other objects and features of the present invention will become more fully apparent from the following description and appended claims taken in conjunction with the accompanying drawing.