US3282449A

US3282449A - Truck elevator safety mechanism

Info

Publication number: US3282449A
Application number: US405955A
Authority: US
Inventors: Charles Y Buford
Original assignee: Darling and Co
Current assignee: Darling Ingredients Inc
Priority date: 1964-10-23
Filing date: 1964-10-23
Publication date: 1966-11-01
Anticipated expiration: 1983-11-01

Description

Nov. 1, 1966 c. Y. BUFORD TRUCK ELEVATOR SAFETY MECHANISM 2 Sheets-Sheet l Filed Oct. 25, 1964 lfzvQnior Y CharlesYuford 33g/ jf'i-ow, N

Ei .i

S i XN Nov. l, 1966 c. Y. BUFoRD 3,282,449

TRUCK ELEVATOR SAFETY MECHANISM Filed Oct. 23, 1964 2 Sheets-Sheet 2 Inventor Charles Y, Buford.

United States Patent O 3,282,449 TRUCK ELEVATUR SAFETY MECHANESM Charles Y. Buford, Elmhurst, lll., assignor to Darling 8: Company, Chicago, lli., a corporation of Illinois Fied Oct. 23, 1964, Ser. No. 405,955 Claims. (Cl. 214-75) The present invention relates generally to elevator apparatus for a vehicle and more particularly to safety mechanism for elevator apparatus of vehicles such as trailers and trucks which have the vertical movement of a load support member controlled by a flexible lift means.

Vehicles such as trailers and trucks which are used to carry large containers or pallets loaded with cargo or freight are frequently provided with elevator apparatus which is adapted to move the containers or pallets from ground level to the level of the truck deck or oor during loading or unloading operations and which use a flexible cable for lifting or lowering the load-supporting platform. Because of the heavy loads the vehicle elevator apparatus is required to support, there -is danger of injury to the cargo and the operators in the event a lift cable or the hoist mechanism controlling the lift cable breaks. Various types of safety latches and other mechanism have been devised to prevent damage to goods and personnel as a result of the lift cable parting or the hoist mechanism to which the cable is attached breaking. Because of the complexity and added cost of such safety devices, there has been no wide spread adoption thereof.

It is therefore an object of the present invention to provide an improved safety means for elevator apparatus having the vertical movement of a load support member controlled by a exible lift means.

It is a further object of the present invention to provide an improved safety mechanism associated with a lift cable of a vehicle elevator apparatus which is simple in construction and reliable in operation.

A still further object of the present invention is to provide an improved truck elevator safety mechanism which can be applied to existing elevator apparatus employing a lift cable without extensive modification thereof.

Other objects of the present invention will be evident to those skilled in the art from the following description and claims when read in conjunction with the accompanying drawing, wherein:

FIG. 1 is a fragmentary schematic perspective view of an elevator apparatus with the safety mechanism of the present invention operatively mounted on a truck body;

FIG` 2 is a fragmentary vertical sectional View taken along the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary vertical sectional view showing the safety mechanism of the present invention in retracted position;

FIG. 4 is a fragmentary horizontal sectional view taken along the line 4-4 of FIG. 3; and

FIG. 5 is a fragmentary vertical sectional view showing the safety mechanism of the present invention in extended position.

Since the specific structure of the truck body and elevator assembly mounted thereon is not the subject of the present invention, only so much of the foregoing structures are shown as is necessary to disclose the elevator safety means which comprises the subject matter of the present invention.

As illustrated in FIGS. 1-5 of the drawing, the vehicle elevator apparatus in which the principal safety mechanism of the present invention is embodied for purposes of illustration comprises generally a load-supporting lift gate or lift platform adapted to be disposed in a horizontal position with the opposite inner corners thereof pivotally connected by

suitable brackets

13, 14 with the 3,282,448 Patented Nov. l, 1966 lower ends of generally square

tubular lift members

16, 17, respectively. Each of the

lift members

16, 17 is slidably disposed in one of the spaced parallel generally rectangular, tubular guide means 11, 12, such as lengths of slotted square steel tubing, extending vertically from just above ground level to slightly above the top of the truck body 15 and rigidly connected to each other by the truck body 15 at the rear corner portions of the frame thereof. A longitudinal opening or slot is preferably provided in the

rear walls

19, 20 of each the guide means 11, 12 to accommodate the vertical movement of the

brackets

13, 14 secured to the lift gate 10. The guide means 11, 12 also are provided on the

inner wall sections

21, 22 thereof with a plurality of plunger pin-receiving means or apertures 24 which are spaced a few inches apart starting at a point adjacent the top and extending to a point adjacent the bottom of the

guide members

11, 12.

The

tubular lift members

16, 17 are adapted to be slidably suspended within the spaced guide means 11, 12 by a flexible cable 18 or an equivalent exible lift means which has the opposite ends thereof secured to the lower ends of each of the

lift members

16, 17 and extends aX- ially the length of the

lift members

16, 17. The lift cable 18 passes over

idler sheaves

23, 23 adjacent the upper end portion of each of the spaced guide means 11, 12 and is operatively connected to a hoist mechanism by sets of oppositely disposed

sheaves

26, 27, as will hereinafter be described.

The vertical movement of the

tubular lift members

16, 17 and in turn the raising and lowering of the lift gate 10 is controlled by raising and lowering the ends of the cable 18 through any suitable hoist mechanism, including a motor-actuated reel or a hydraulic-actuated assembly. In the form of hoist mechanism 25 illustrated in the drawing, a plurality of oppositely disposed spaced sheaves or pulleys are employed with one set of the sheaves 26 rotatably mounted on a stationary transverse rod or axle at one end of a hydraulic cylinder 28 and another set of sheaves 27 rotatably mounted on a second transverse axle which is movable by means of the hydraulic piston rod 29 of the hydraulic cylinder` 28. It will be evident that the lower ends of the lift cable 18 can be raised or lowered as the sheaves 27 are moved toward or away from the sheaves 26 by means of the hydraulic cylinder 28. The hydraulic cylinder 28 is controlled by a valve control rod 33 operatively connected with a valve 34 which regulates the tiow of hydraulic uid from a fluid reservoir 35 through a fluid pump 36 driven by a power takeolf from the engine of the truck. Other means, of course, can be provided for driving the Huid pump, if desired.

The safety mechanism 40 with which the present invention is primarily concerned coacts with

lift members

16, 17 and the

gruide members

11, 12 to prevent relative longitudinal (i.e., vertical) movement therebetween when the normal tension .on the lift cable 18 is removed for any reason, such yas breakage of the cable 18 or lfailure of any of th'e parts to which the cable 18 is operatively connected and associated. More particularly, the safety mechanism 40 comprises one or more spring-actuated plunger pins 41 slidably mounted in a guide passage 42 formed in the inner wall :of the

lift members

16, 17 and preferably spaced a short distance from the lower ends thereof. A tubular sleeve member 43 is preferably secured to the inner surface of the outer vertical wrall section of each of the

lift members

16, 17 and supports a pin-actuating means which :in the form illustrated cornprises a compression spring 45. The plunger pins 41 lare normally disposed in retracted position within the wall sections of the lift members 1d, 17 whzile the elevator apparatus and calble 18 yare in operating condition with normal tension on the lift cable 18. However, the

pins 41 are adapted to move transversely through the guide passage 42 for-med in -a wfall section of the

tubular lift members

16, 17 into engagement with plunger pinreceiving means 24 formed in a wall of the

guide rnembers

11, 12 when normal tension on the lift cable 18 is lost `for any reason. Each of the plunger pins 41 has a transverse passage extending diametrically therethrough at a point preferably midway between the ends thereof and through which the 'lift cable 18 can freely pass. A lint washer 44 is mounted over the outer end of the plunger pin 41 Iand engages the lift cable 18. The compression spring 45 having a diameter slightly larger than the pin 41 is seated within a sleeve member 43 with the outer end of the spring 45 supported Within the sleeve member 43 and engaging outer wall of the

lift members

16, 17. The plunger pin 41 is adapted to be received Iaxially within the coils of the spring 45 with the washer 44 engaging the inner end of the spring 45. An access opening 46 is formed in the side of

tlhe lift members

16, 17 opposite each of the sleeve members 43 to facilitate assembly land repair of the safety mechanism 40.

The plunger pins 41 are preferably cylindrical in cross section and have a length slightly less than the transverse width of the

tubular lift members

16, 17 so that the outer end Iof the pins 41 whenfin retracted position are dispo-sed Within the sleeve members 43 with the Iinner end s'lidably supported in the guide passage 42 in the inner wall section of the lift members, 16, 17. The plunger pins 41 in the for-n1 illustrated preferably have `a diameter of about 9% of an inch, a maximum sheer yload of about 22,000 lbs. and ,a safe shock load of 2,500 lbs. The size and strength of the pins 41 can, of course, be varied depending upon the size of the elevator apparatus. It will be understood, however, that the dimensions of the pins 41 can vary depending upon the materials used and the load requirements of the particular unit. v

From the foregoing description it will be evident that when there is tension on the lift cable 18 either due to the weight of the lift gate 10 or as a result of the pull exerted by the lhoist mechanism 25, the cable 18 is main tained in substantially vertical or axial position within the

lift members

16, 17. With the cable 18 disposed Iaxially in the

lift members

16, 17, the plunger pins 41 which are engaged by the cable 18 are held in a retracted position within the

lift members

16, 17 with the inner end of each plunger pin 41 slidably supported by la guide passage 42 fand with the spring 45 under compression as the result of the cable urging the Washer 44 tnansversely toward the 4outer Wall of the

lift members

16, 17, 4as best shown in FIG. 4 of the drawing.

When the normal tension on the cable 18 is 'lost due to the cable 18 breaking or the associated hoist mechanism failing, the cable becomes slack and the compression spring 45 acting aga-inst washer 44 urges the pins 41 transversely. As the

lift members

16, 17 descend within the guide means 11, 12, the plunger pins 41 will coincide with one of the sevenal vertically spaced apertures 24 formed in the

inner wall sections

21, 22 of the

guide members

11, 12 and the plunger pins 41 will engage in the plunger pinareceiving aperture 24, whereupon the pins 41 serve as a key locking the lift members. 16, 17 and the guide means 11, 12 against funther relative vertical movement and prevent further descent of the lift gate 10, as best shown in FIG. of the drawing. With a plunger pin 41 having a diameter of about 3/4 of an inch and with a compression spring 45 formed of siX coils Iof .115 inch spring Wire with an uncompressed length of 11/2 inches and a load rate of 50 pounds, it has been found desirable to have the passages 24 in the form of oval slots 11/2 inches long and 'Ma of an inch in diameter in order to insure the entry of the plunger pins 41 in the lirst of tbe apertures 24 with which the plunger pins coincide after the lift gate 10 begins its descent when the lift cable 18 breaks or tension is lost in the lift cable 18 for any other reason. As soon as tension is restored to the cable 18 the pins 41 Iare returned to their normal retracted position within the

lift members

16, 17 and the lift igate 10 can be moved vertically in the normal operation of the elevator apparatus.

It will be understood that the optimum dimensions of the passage 24 will depend Ion the size of the pin 41 Iand the type of spring used and lthe invention is in no Way limited to the use of any particular part or passage dimension.

It will be also evident that the safety mechanism 40 as above described is adapted for use with iany elevator apparat-us employing a lift cable #for vertically moving the lift gate .and having la lift member attached to the lift gate and operatively associated with a lixed guide means. And, While the prefer-red embodiment of the invention shows a load-supporting means and lift members supported between two spaced guide means, it is also possible to empl-oy the safety mechanism of the present invention in an elevator structure having a single lift member movable vertically relative to a single fixed guide means, as in a forked lift truck apparatus.

I claim:

1. In a vehicle having in combination Aan elevated loadsupporting floor, -an elevator apparatus mounted on said vehicle and adapted to move vertically between the ground level and the level of said supporting iioor with said elevator apparatus including a load-supporting member and at least one vertical lift member attached thereto land supported for vertical movement -relative to a fixed vertical guide means by a exible lift means and having power means connected 'with said lift-supporting element w|hich is yadapted to raise yand lower said .load support member, the improvement comprising; a spring actuated plunger pin mounted on said lift member .and engageable by said ilexible lift means, said iiexible lift means adapted to be in engagement with said plunger pin intermediate the ends of said lift mean-s and hold said plunger pin .in .retracted position while said flexible lift means remains under normal tension and allow said plunger to extend outwardly from said lift member when said flexible .lift means is with-out normal tension, and .a plurality of plunger pin receiving means formed in said guide means with which said plunger pin is adapted to engage when said exible lift means is without normal tension; whereby said guide means and said lift member are locked against relative vertical movement until tension is `restored to said flexible lift means.

2. In a vehicle having an elevated load-supporting door, an elevator apparatus mounted on said vehicle and adapted to move vertically between the ground level and the level of said supporting floor with said elevator apparatus including a load-supporting member and at least one vertical lift member attached thereto and supported for vertical movement relative to `a fixed vertical guide means by a lift cable xand lhaving power means connected with said cable which -is adapted to raise and lower said loa-d support member, the improvement comprising; ya spring actuated plunger pin mounted for transverse movement lin .a guide formed in said lift member, said pin having a transverse passage through which said lift cable is adapted to pass and hold said plunger pin in retracted position in said guide While said cable remains under normal tension and allow said plunger to extend outwardly through said guide when said cable is without normal tension, anda plunger pin receiving means formed in said guide means in which one end of said plunger pin engages when said cable is Without normal tension; whereby said guide means `and said lift member are locked against relative vertical movement until tension is restored to said lift cable.

3. 1n a vehicle having an elevated load-supporting floor, an elevator apparatus mounted on said vehicle and .adapted to move vertically between the ground level and the level of said s-upportnig floor With said elevator apparatus including a load-supporting member and at least one vertical lift member attached thereto and supported for vertical movement relative to a xed vertical guide means by a lift cable Iand having power means connected with said cable which is adapted to raise and lower said load support member, the improvement comprising; a plunger pin mounted for transverse movement relative to said lift member in a guide formed integrally with said lift member, a spring means mounted on said lift member 'and operatively associated with said pin normally urging said pin transversely in sai-d guide, said plunger pin having -a passage extending transversely therethrough between the ends thereof through which said lift cable is adapted to ,pass and hold said pin in retracted position in said guide while said cable remains under normal tension and allow one end of said plunger pin to extend transversely beyond said lift member when said cable is without normal tension, `and said guide means having plunger pin receiving means in which said one end of plunger pin is adapted to engage when tension is removed from said lift cable; whereby said guide means and said lift member are locked against relative vertical movement until tension is restored to said li-t cable.

4. In a vehicle having an elevated load-supporting floor, an elevator apparatus mounted on said vehicle and adapted to move vertically between the ground level `and the level of said supportnig oor with said elevator apparatus including a load-supporting member and spaced vertical lift members attached thereto and suppo-rted for vertical movement within vertical guide means by a lift cable and having power means connected with said cable which is adapted to raise yand lower said load support member, the improvement comprising; a plunger pin mounted in a guide formed in each of said lift members for transverse movement relative to said lift mem-bers, a spring means mounted on each of said lift members and operatively lassociated with each said pin normally urging said pin transversely of said lift member in said guide, each said plunger ,pin having a passage extend-ing transversely therethrough between the ends thereof:` through which said lift cable is adapted to pass and which holds said pin in retracted position in said guide while said cable remains under normal tension and allow one end of said plunger pin to extend transversely beyond `said lift member when said cable is without normal tension, and a plurality of plunger pin receiving means formed at spaced points Ialong the length of said guide means facing said guide of `said lift member in which said one end of said plunger pin is |adapted to engage when tension i-s removed from said lift cable; whereby said guide means and lift members are locked Iagainst rela-tive vertical movement until tension is restored to `said lift cable.

5. An elevator lapparatus as in claim 4, wherein said pin receiving means comprises elongated passages formed in said guide means having a length -at least about twice the diameter of said plunger pins.

References Cited by the Examiner UNITED STATES PATENTS 4/ 1912 Tozser 8/ 1962 Bartlett

Claims

1. IN A VEHICLE HAVING IN COMBINATION AN ELEVATED LOADSUPPORTING FLOOR, AN ELEVATOR APPARATUS MOUNTED ON SAID VEHICLE AND ADAPTED TO MOVE VERTICALLY BETWEEN THE GROUND LEVEL AND THE LEVEL OF SAID SUPPORTING FLOOR WITH SAID ELEVATOR APPARATUS INCLUDING A LOAD-SUPPORTING MEMBER AND AT LEAST ONE VERTICAL LIFT MEMBER ATTACHED THERETO AND SUPPORTED FOR VERTICAL MOVEMENT RELATIVE TO A FIXED VERTICAL GUIDE MEANS BY A FLEXIBLE LIFT MEANS AND HAVING POWER MEANS CONNECTED WITH SAID LIFT-SUPPORTING ELEMENT WHICH IS ADAPTED TO RAISE AND LOWER SAID LOAD SUPPORT MEMBER, THE IMPROVEMENT COMPRISING; A SPRING ACTUATED PLUNGER PIN MOUNTED ON SAID LIFT MEMBER AND ENGAGEABLE BY SAID FLEXIBLE LIFT MEANS, SAID FLEXIBLE LIFT MEANS ADAPTED TO BE IN ENGAGEMENT WITH SAID PLUNGER PIN INTERMEDIATE THE ENDS OF SAID LIFT MEANS AND HOLD SAID PLUNGER PIN IN RETRACTED POSITION WHILE SAID FLEXIBLE LIFT MEANS REMAINS UNDER NORMAL TENSION AND ALLOW SAID PLUNGER TO EXTEND OUTWARDLY FROM SAID LIFT MEMBER WHEN SAID FLEXIBLE LIFT MEANS IS WITHOUT NORMAL TENSION, AND A PLURALITY OF PLUNGER PIN RECEIVING MEANS FORMED IN SAID GUIDE MEANS WITH WHICH SAID PLUNGER PIN IS ADAPTED TO ENGAGE WHEN SAID FLEXIBLE LIFT MEANS IS WITHOUT NORMAL TENSION; WHEREBY SAID GUIDE MEANS AND SAID LIFT MEMBER ARE LOCKED AGAINST RELATIVE VERTICAL MOVEMENT UNTIL TENSION IS RESTORED TO SAID FLEXIBLE LIFT MEANS.