US 3279755 A
Description (OCR text may contain errors)
Oct. 18, 1966 J. NOTENBOOM ET AL 3,279,755
MULTI-STAGE HYDRAULIC HOIST Filed Jan. 11, 1965 2 Sheets-Sheet 1 INVENTORS ATTORNEYS United States Patent 3,279,755 MULTI-STAGE HYDRAULIC HOIST Leo J. Notenboom, Harold M. Peterson, and Joseph J.
Pfeilfer, Kirkland, Wash., assignors to ReDeMan Corporation, a corporation of Washington Filed Jan. 11, 1965, Ser. No. 424,687 8 Claims. (Cl. 254-93) This invention relates to a hydraulic hoist mechanism, multi-stage by preference, engineered in particular for use in raising and lowering a work platform such, for example, as a scaffold. The hoist has a piston which works within a cylinder and is carried upon the lower end of a stanchion smaller in diameter than the cylinder, and there is secured in the outer end of the cylinder both as a stop for the piston and as a guide for the stanchion a header which is given a close spline fit with the stanchion.
The hoist employs multiple piston-cylinder assemblies to produce a telescoping standard and it is one object of the invention to devise a system in which hydraulic fluid supplied under pressure acts first upon the outermost piston-cylinder assembly to extend the same to its maximum height and then extends each succeeding pistoncylinder assembly in turn, with the speed of rise being approximately uniform in each instance.
Another Object of the invention is to provide hoist mechanism of the described nature which conveniently adapts itself to various types of mounting supports as, for example, an automotive truck or wheeled struts.
As a further object the invention aims to provide a telescoping hydraulic hoist in which each of the hoist cylinders and their pistons are positively held against rotation.
The invention has the additional object of providing a telescoping hydraulic hoist which is substantially proof against leakage.
The above and yet further objects and advantages in view, looking to the provision of a hoist requiring little servicing attention and which is of strong, durable and relatively inexpensive construction, will appear and be understood in the course of the following description and claims. The invention consists in the novel construction and in the adaptation and combination of parts hereinafter described and claimed.
In the accompanying drawings:
FIGURE 1 is a fragmentary view partly in vertical section and partly in elevation illustrating a telescoping hydraulic hoist constructed to embody preferred teachings of the present invention.
FIG. 2 is a fragmentary horizontal sectional view thereof on line 22 of FIG. 1.
FIG. 3 is a fragmentary horizontal sectional view drawn to an enlarged scale on line 3-3 of FIG. 2.
FIG. 4 is a fragmentary enlarged scale vertical sectional view on line 44 of FIG. 3.
FIG. 5 is a fragmentary enlarged scale horizontal sectional view on line 55 of FIG. 1; and
FIG. 6 is a perspective view indicating the hoist in association with a portable mounting comprised of wheeled struts.
In said drawings we have shown the hoist as being three-stage, and referring to such drawings the numerals 10, 11 and 12 denote interfitting cylinder members for the first, the second, and the third stages, respectively. Each said cylinder member is open at the top with internal threads surrounding its top opening, and at the bottom provides an end wall, as 13, 14 and 15. Each of these end walls has a through-bore, as 16, 17 and 18, in its center, sized so that, for each of the three cylinders, much the same ratio exists as between its areal compass and 3,279,755 Patented Oct. 18, 1966 the flow capacity of the bore which is provided in its end wall. The bore 16 is tapped to receive suitable fittings 20 accommodating a flexible hose which connects the hoist with a 3-position control valve (not shown), such valve either supplying from a pump a governed volume of pressure fluid to the hoist, locking the fluid in the hoist, or dumping such fluid to a reservoir from which the pump draws its supply.
The outer cylinder member 10 serves as a base for the hoist, and is provided exteriorly with two set of vertically spaced circumferential grooves adapted to receive snap-rings 21. The two sets of snap-rings are located one adjacent the top and one adjacent the bottom of the cylinder member, and each is adapted to hold a respective one of two collars, as 22 and 23, in place upon the cylinder member. The collars present a shoul der at one end and at the other end are threaded. A pair of mounting rings, as 24-25 and 26-27, are journaled for turning motion upon the collars, occupying positions one above the other between the shoulder and a locktype keeper ring 28 which threads on the collar. As can be understood from an inspection of FIG. 6, eyed lugs extend radially outwardly from each mounting ring at diametrically opposite sides thereof, and legs for the standard are attached to these lugs. The legs and the manner of their attachment to the standard are the subject matter of a separate application now in process of preparation but suflice it to here say that each leg carries a ground wheel 30 together with a ground-engaging screw jack 31 at its outer end, comprises inner and outer sections articulating for relative swing motion about a vertical axis, and has upper and lower arms which diverge toward the collars.
Proceeding now to describe the extension mechanism of my multi-stage hoist, the first-stage cylinder member 10 has an inside diameter substantially larger than the outside diameter of the second-stage cylinder member 11. The second-stage cylinder member likewise has an inside diameter substantially larger than the outside diameter of the third-stage cylinder member 12. Such third-stage cylinder member, in turn, has an inside diameter substantially larger than the outside diameter of a cylindrical stanchion 33 which is received therein. The spaces 34, 35 and 36 which are thereby provided are occupied by three pistons 37, 38 and 39. Each piston is ring-shaped and is carried at the lower end of the cylinder member 11, the cylinder member 12, or the stanchion 33, as the case may be. The pistons each fit a necked-down portion (see FIG. 4) which is provided at the lower end of the related member. The pistons are held in place by snap-rings 40 seating in circumferential grooves. Each piston has a static seal 41 at the inside, and at the outside is fitted with a compression seal 42 and a wear strip 43. The static seal is or may comprise a neoprene O-ring. A nylon belt is suitable as a wear strip, and for the compression seal we prefer to employ an O-ring of neoprene occupying a downwardly facing skirted pocket formed in a band of self-lubricating plastic such, for example, as graphited polyurethane. By reason of the differences in diameter the lift capacity of the surface 14-37 is greater than that of the surface 15-38, and the latter is in turn greater than that of the horizontal surface exposed by the stanchion including its piston 39.
Extending between the necked-down portions and the upper extreme end of each of said members 11, 12 and 33 there is provided a longitudinal groove, as 44, 45, and 46. These grooves each accommodates a key, as 47, 48 and 49, extending inwardly from a respective one of three glands 50, 51 and 52, or headers as they will be hereinafter termed. The headers are externally threaded to engage said internal threads which lie at the upper end of the three cylinder members 10, 11 and 12, being locked against turning by Allen-headed screws 53. Header 50 closely fits the cylinder member 11. Header 51 closely fits the cylinder member 12. Header 52 closely fits the stanchion. A respective ring 57 of filter material, felt for example, is carried by each header in a suitable groove extending circumferentially about the inner perimeter, and serves to pass air into and from the spaces 34, 35 and 36 as the pistons move therein. A respective snap-ring, as 54, 55 and 56, received in a circumferential groove located a moderate distance above each piston acts by its engagement with the related header to prescribe for the pistons a maximum length of travel such that each of the three members 11, 12 and 33, when fully extended, retains a stable bearing against lateral deflection. Should any air be present in the hydraulic system the same is bled by a valve 58 from the head end of an open-bottom center bore 59 formed in the stanchion.
When applied to the use for which the same has been primarily designed, namely the support of an elevatortype scaffold, two hoists each mounted so as to be substantially vertical are used with one end of the scaffold bearing upon the head end of one stanchion and the other end bearing upon the head end of the other stanchion. The collar 22 has radial arms which carry levelling bubbles. Should it be desired, the hoists and scaffold can be mounted upon a truck. It is preferable in such an application that the lower end of the hoist have a gimbal mounting and for this purpose we prolong the outer cylinder member below its bottom wall and provide bearings 60 for trunnion pins (not shown). The lower set of mounting rings 26-27 are dispensed with, and a respective one of two strutseach adjustable as to length by a turn-buckle-is attached to each of the two mounting rings 24-25. The two struts extend diagonally from the hoist to a suitable anchor fitting provided on the truck, one occupying a longitudinal vertical plane and the other a transverse vertical plane.
As will, it is thought, be apparent hydraulic fluid delivered under pressure to the hoist first exerts thrust upon the bottom wall of the cylinder member 11. Such member, together with the cylinder member 12 and the stanchion 33, rise bodily until the snap-ring 54 is brought against the head-ring 50. The cylinder member 12 continues to rise until its travel is interrupted by the engagement of snap-ring 55 with the head-ring 51. Stanchion 33 then provides the third-stage rise of the hoist. It will be noted that annular ribs protrude below the bottom 'wall of the two cylinder members 11 and 12 so that each of said bottom walls exposes a large area to the -lift pressure of the incoming hydraulic fluid.
It is believed that the invention will have been clearly understood from the foregoing detailed description of our now-preferred illustrated embodiment. Changes in the details of construction may be resorted to without departing from the spirit of the invention and it is accord- .ingly our intention that no limitations be implied and that the hereto annexed claims be given the broadest interpretation to which the employed language fairly admits.
What we claim is: 1. A hoist comprising a body member having an open- 'top annular cylinder of extended length therein with a closing wall at the bottom, said bottom wall having an opening for delivering fluid under'pressure to the cylin der and for dumping said fluid therefrom, a piston of comparatively short length fitting said cylinder, a stanchion of circular cross-section having a diameter substantially less than that of the cylinder and a length at least as long as the cylinder received within the cylinder, means attaching said piston to the lower end of the stanchion, a header having a spline fit upon the stanchion and occupying the space between the stanchion and the body member at the top end of the cylinder, and means detachably securing said header to the body member holding the header against displacement in a direction endwise to the cylinder, the lower end of the stanchion being necked down to provide a seat for the piston, the interior and exterior surfaces of the piston being circumferentially grooved, sealing rings being received in both of said grooves.
2. In a multi-stage hydraulic hoist: a series of interfitting members comprising a stanchion of circular crosssection at the inside, a cylinder member at the outside, and at least one median cylinder member therebetween, the cylinders of said median and outer cylinder members being open at the outer end, closed at the inner end, and having adiameter which is in each instance substantially larger than the outside diameter of the next smaller member of the series, the walls which close said inner ends having through-openings therein for delivery of pressure hydraulic fluid to and dumping of hydraulic fluid from the cylinders, said inner cylinder member and the stanchion each having an annular piston carried upon the lower end thereof closely fitting the wall of the surrounding cylinder, sealing rings for the pistons, and a respective header carried by each cylinder member at the outer end thereof having a close spline fit with the next smaller member of the series.
3. A hydraulic hoist according to claim 2 in which the through-opening in the wall which closes the inner end of the outer cylinder member is appreciably larger than that which closes the inner end of the median cylinder member.
4. A hydraulic hoist according to claim 2 in which the stanchion has a center-bore extending the substantial length thereof with the lower end open for access of hydraulic fluid from the cylinders of the hoist and with the upper end closed by an air-bleeding valve.
5. A hydraulic hoist according to claim 2 in which the spline fit provided for each header comprises a key carried by the concerned header received for sliding movement in a key-way formed in the member which it fits, each header being formed interiorly with a circumferential groove, and having a ring of filter material seated therein.
6. A hoist as claimed in claim 2 in which both the inside and the outside surface of each piston is circumferentially grooved and having a respective one of said sealing rings received in each groove the inner ring to produce a static seal and the outer ring to produce a compression seal, said outer surfaces being each provided with an additional circumferential groove to receive a wear strip.
7. A hoist as claimed in claim 2, and upper and lower mounting collars sleeved upon the outer cylinder each having a respective pair of mounting rings journaled for rotation thereon.
8. A hoist comprising a body member having an opentop annular cylinder of extended length therein with a closing wall at the bottom, said bottom wall having an opening for delivering fluid under pressure to the cylinder and for dumping said fluid therefrom, a piston of comparatively short length fitting said cylinder, a stanchion of circular cross-section having a diameter substantially less than that of the cylinder and a length at least as long as the cylinder received within the cylinder, means attaching said piston to the lower end of the stanchion, a header having a spline fit upon the stanchion and occupying the space between the stanchion and the body member at the top end of the cylinder, means detachably securing said header to the body member holding the header against displacement in a direction endwise to the cylinder, said spline fit between the stanchion and the header comprising a key provided by the header and received in a key-way provided by the stanchion, the header being formed interiorly with a circumferential groove, and a ring of filter material seated in said interior groove and having a profile configuration, interior surface considered,
5 6 corresponding to the exterior profile of a cross-section of 2,143,182 1/ 1939 Barr. the stanchion including the key-way. 2,854,958 10/195 8- Wood et a1 9253 References Cited by the Examiner 6/1964 Walker 91 168 UNITED STATES PATENTS 5 WILLIAM FELDMAN, Primary Examiner. 1,069,863 8/1913 DBSPiIIS 91 -169 X OTHELL SIMPSON E j 2,002,428 5/1935 Black.