US1962220A - Hydraulic vehicle lift - Google Patents

Description

June 1934- L. c. STUKENBORG HYDRAULIC VEHICLE LIFT Filed Jan. 20, 1933 Patented June .12, 1934 UNITED STATES PATENT OFFICE 1,962,220 mmumovnmonn m'r Louis stukenborg, Memphis, Trm. Application January 20, 1933, Serial No. 652,585

Claims. (01.138f-9) hicle, thus uselessly continuing the use of electric This invention has general reference to hoisting or elevating devices in which there is employed a vertically-disposed cylinder, a hollow plunger therein which acts as a reservoir for the fluid used as a power medium, and a 'motor-.

driven pump for effecting the transfer of such' fluid from the plunger to the cylinder, the motor and plunger being carried by the plunger, and raised and lowered therewith. However, particular reference will be made hereinafter to the combination with such devices of means by which the current-transmission cable will lead to the -motor in a way materially different from the leads known and employed heretofore, and to means for automatically cutting off the currentconnection to the motor at a predetermined height of lift, so that, incidentally, the height of rise of the plunger may thus be automatically limited. f

In hydraulic lifts in which the motor is raised and lowered with the plunger, the provision of means for supplying current to the motor always has involved numerous difficulties, particularly in vehicle lifts of the rotary type. In such lifts, the manner of use prohibits leading the cable to the motor from thereabove, or the provision of pits wherein the cable may be received when the de- "vice is lowered, and therefore requires that the cable be, led to the motor approximately at the level of the surface in which the lift is installed, and that sufficient excess cable be providedat or near the lifting device to allow for the lifting movement of the plunger. Such excess cable is subject to kinking, and to damage by the vehicle prior or subsequent to its being raised, and is open to the further objection that it is likely to be in theway of anyone who may be working on the elevated vehicle. In efforts to avoid the foregoing objections, the makeshift has been adopted of leading the cable along one of the rails that form part of the lift superstructure, and utilizing a slip or other type of coupling which provides for disconnection of the cable whenever electric current no longer is required, such disconnection being necessary in order that the lift superstructure may be rotated, as well as for the purpose of removing the cable as an obstruction. The type of vehicle lifts herein referred to, ordinarily are equipped with some means whereby, when the liftsuperstructure has reached a predetermined height, further fluid pressure becomes ineffective; and it therefore has become common practice to permit the motor to continue in operation after completion of the raising operation, 55 and even during the servicing of the raised vecurrent.

The present invention is intended to provide simple and efficient means whereby the foregoing and other objection may be obviated, and to that end the primary object of the invention set forth herein is to improve upon the heretofore-known means of supplying electric current to the motors of vehicle lifts and the like, particularly in the following respects, it being intended that such improvements shall likewise be applicable to hoisting or lifting devices other than those employed for raising vehicles:

First. By disclosing means whereby a powertransmission cable may be lead to a lifting or hoisting device in such manner that any slack insuch cable will be taken up automatically dur- -'cable.

Fourth. By disclosing means whereby lowering of the device will automatically restore the power circuit to operative condition.

The means by which the foregoing and other objects are accomplished by my present invention, and the manner of their accomplishment, readily will be understandable from the following description on reference to the accompanying drawing, in which- Fig. 1 is a sectional elevation of a portion of a vehicle lift having my improvements applied thereto.

Fig. 2 is a transverse sectional elevation, the section being taken substantially on the line II-II of Fig. 1.

Fig. 3 is a diagrammatic view showing the power-transmission circuit and one arrangement of the cut-off switch.

' Referring now to the details of the drawing,

13A secured thereto, so as toconstitute what is commonly designated as a free-wheel type of lift table. Mounted in the upper end of the plunger 11, is an electric motor 14, which is directly connected by a shaft 15 with a pump 16 by which fluid is transferred from the plunger 11 to the cylinder 10. 17 is a release valve, which is manually operable to permit lowering movement of the plunger 11. The details of the foregoing parts, not being pertinent to the inven tion herein claimed, are not illustrated in the drawing. and will not be described herein in detail. 7

Current to actuate the motor, is brought in from the usual power line 20 through a hand-operated switch 21 from which circuit wires 22, preferably grouped in a cable 22A, lead to the motor 14. Preferably the cable is enclosed, to a point adjacent the cylinder 11 and vertically below the head 12, in a conduit 23. This conduit usually will lead beneath the floor 24 and terminate as at 25 pointing vertically upward. From the conduit, the cable 22 is carried vertically upward to a grooved roller 26 over which it passes to a horizontally disposed roller 27, a complementary roller 28 being preferably used in connection with the roller 26 to prevent accidental displacement of the cable. The cable passes around the roller 27 and thence horizontally along the rail 13 toward the free end of the rail. A bight is formed in the cable around a roller 29 and the cable lead back along the rail to the motor 14.

Preferably a cut off switch, generally indicated by the numeral 30, is interposed in the cable line adjacent the head 12, which switch automatically interrupts the circuit at a predetermined point, terminating the plunger rise.

The switch 30, includes poles 31 and a contact bar 32 normally held in contact therewith, as by a compression spring 33, to complete'the circuit. The contact bar is disengaged to break the circuit by movement of the pulley shackle 34 against a head or button 35 connected to the bar. A spring 36 maintains tension on the pulley 29 to take up slack in the cable. In use the hand switch 21 is closed to start the motor. As the lift rises, the cable 22A moves the pulley 29 toward the motor and switch until at a predetermined height thepulley shackle 34 strikes the button 35 and disengages the contact bar from the poles, terminating flow of current to the motor, and consequent rise of the plunger.

On completion of use the plunger is lowered in usual manner by use of the release valve 17. As the plunger lowers, the spring 36 automatically takes up the cable slack released by such lowering and incidental to such take up, restores the power circuit so far as the switch 30 is concerned. Ordinarily the hand switch 21 has been opened also and such action does not restart the motor.

Should this have been overlok ed it is necessary to open the latter switch, or greatly delay if not entirely stop the lowering of the plunger.

It will be seen that at all times, subsequent to, during, and after use the cable 22A is so cared for as to afford the maximum available protection thereto and as to minimize its interference with access to the lift or the vehicle thereon for servicing.

Ordinarily rotary movement of vehicle lifts is limited to a comparatively small arc of the complete circle and also occurs only in raised position. Under such circumstances that portion of the cable extending upward from the terminus 25, of the cable conduit, will wrap around the plunger without serious interference with such rotation of the lift, or damage to the cable.

Having described my invention, what I claim is:

1. In a device of the character described, comprising a cylinder, a plunger slidable therein, a motor carried by and movable with said'plunger, and a pump driven by said motor for imparting movement to said plunger, the combination, with a cable for supplying electric current to said motor, of an automatic take-up for said cable, and a switch through which said cable leads, said switch having means co-operable with said takeup to open the switch when said plunger reaches a predetermined height.

. 2. In a device of the character described, comprising a cylinder, a plunger slidable therein, a support on said plunger, a motor carried by and movable with said plunger, and a pump driven by said motor for imparting movement to said plunger, the combination, with a cable for supplying electric current to said motor, the lead of said cable being such as to form a bight therein on said support, of a pulley in said bight, a switch through which said cable leads, means for moving said pulley to take up slack in said cable during raising and lowering operations of said plunger, and means for throwing said switch by movement of said pulley.

3. In a vehicle lift, including a vertically disposed cylinder, a plunger slidable therein, a head secured to said plunger, a pair of vehicle-supporting rails secured to said head and extending longitudinally therefrom, a motor carried by said plunger and means driven by said motor for sliding said plunger; the combination with a conduit terminating adjacent said cylinder in a vertically disposed portion, a pulley journalled on said head above the end of said conduit, a laterally disposed pulley journalled on one of said rails, a movable pulley-shackle disposed against said rail between said head and the end of said rail, a pulley journalled in said shackle, and a tension spring having one end secured adjacent the end of said rail and the other end secured to said shackle, I

of a cable for supplying current to said motor, disposed in said conduit and extending vertically upward therefrom, to and over said head-pulley, said rail-journalled pulley and said movable pulley and leading from the latter back along said rail to said motor, whereby tension of said spring on said cable will prevent the formation of slack in said cable during movement of said plunger.-

ley journalled in said shackle, and a tension spring having one end secured adjacent the end of said rail and the other end secured to said shackle, of a cable for supplying current to said motor extending vertically upward adjacent said cylinder, said cable leading to and over said headpulley, to said rail-joumalled pulley and said movable pulley and leading from the latter back along said rail to said motor, whereby on upward and downward movement of said plunger said spring will lengthen and retract to pay out and take up slack in said cable.

5. In a vehicle lift, including a vertically disposed cylinder, a plunger slidable therein, vehicle supporting means, including a pair of vehiclesupporting rails, secured to said plunger, said rails extending longitudinally therefrom, a motor carried by said plunger and means driven by said motor for sliding said plunger; the combina tion with a pulley journalled on said means, a pulley, disposed laterally from said first pulley, joumalled on one of said rails, a 'reciprocable pulley-shackle disposed against said rail between said plunger and the end of said rail, a pulley journalled in said shackle, and a tension spring having one end secured adjacent the end 01 said rail and the other end secured to said shackle, of a cable for supplying current to said motor extending vertically upward adjacent said cylinder, said cable leading to and around said pulleys, and leading from said shackle-carried pulley along said rail to said motor, whereby on upward and downward movement of said plunger said springwill lengthen and retract to pay out and take up slack in said cable.

LOUIS C. BTUKENBORG.

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