US2676677A - Telescopic tower - Google Patents

Description

April 27, 1954 A. A. ANDERSON ETAL TELESCOPIC TOWER Filed March 17, 1950 3 Sheets-Sheet 2 Avuo A. Auoaascm BY Rosam- M. HAUCK A-rmduew April 27, 1954 A. A. ANDERSON ETAL TELESCOPIC TOWER 3 She'ets-Sheet 3 Filed March 17, 1950 IIIIIIIIIIIIIIIIIII.

'IIIIIIIIII IIIIIIIIIIII HAUCK A-rronuev Patented Apr. 27, 1954 TELESCOPIC TOWER Arvid A. Anderson and Robert M. Hauck, Milwaukee, Wis., assignors to Safeway Steel Products, Inc., Milwaukee, Wis., a corporation of Wisconsin Application March 17, 1950, Serial No. 150,282

3 Claims.

This invention relates to a telescoping tower particularly adapted for use in maintenance work and similar fields.

An object of this invention is to provide a telescoping tower which may b collapsed to permit free movement through narrow and low doorways while being completely stable when fully eX- tended.

Another object is to provide a tower which may be raised and lowered easily and rapidly with smooth action. 7

Another object is to provide a tower having a central telescoping column actuated by novel hydraulic and mechanical means and having safety means insuring safe descent in the event the actuating mechanism should fail.

Still another object is to provide a telescoping tower which may be manufactured at low cost.

A further object is toprovide a tower which can be raised on a telescopic column which is provided with means for maintaining a precise fit between the parts for the life of the tower, thus insuring stability of the tower.

A still further object is to provide a stable, lowcost, completely safe telescopic tower which may be moved about and. used in restricted areas.

Still another object is to provide a tower having a platform supported on a telescopic column which encloses the hoisting mechanism, thus presenting a neat appearance and preventing fouling the mechanism.

Other objects and advantages will be pointed out in, or be apparent from, the specification and claims, as will obvious modifications of the single embodiment shown in the drawings, in which:

Fig. 1 is a side elevation showing the tower fully extended;

Fig. 2 is a side elevation showing the tower in the collapsed position with the platform guard rail also being shown ina lowered position in dotted lines;

Fig. 3 is a top plan view of the tower;

V Fig, 4 shows the base portion of the tower in its normal position (full lines) and in its collapsed position (dotted lines) permitting passage through narrow doorways, etc.

Fig. 5 is a fragmentary, sectional view of the telescopic column containing the hydraulic and mechanical mechanism for raising and lowering the platform;

Fig. 6 is a fragmentary, sectional view of the air ram which constitutes a safety device preventing rapid descent of the work platform in the event the lifting mechanism should fail;

Fig. 7 shows the air ram of Fig. 6 in its 001- lapsed position; and

Figs. 8, 9 and 10 are sectional views taken as indicated in Fig. 5.

Referring to the drawings in detail, the tele scopic tower is provided with a base comprised of four legs pivotally connected to a central tube it. The legs include a horizontal leg 12 pivotally connected at i 4 to the lower flange It on tube l0 and a downwardly and outwardly projecting strut l8 pivotally connected to the upper tube flange 2i and secured to plate 22 carried by the free end of the horizontal leg [2. Reference to Fig. 4 will show that one pair of diametrically opposed legs 92 may be locked with respect to the lower flange It by dropping a pin 24 through cooperating holes in the leg and flange. Diametrically opposed pairs of legs may b locked with respect to each other by passing a pin 26 through cooperating holes in telescopic members 28, 38 which are pivotally connected to plates 22. Thus when the base is in its normal position (full lines Fig. 4) the telescopic members 28, 38 are locked with respect to each other and one leg of each of the locked pairs of legs is locked with respect to the lower collar or flange It by means of a pin 24. This provides complete stability for thebase. Caster wheels 32 secured to each plate 22 are preferably of the type wherein the wheels may be locked with respect to the rotational axis of the wheel and of the caster swivel, such as shown in the U'ecker et a1. Patent No. 2,262,433.

Should it be necessary to move the tower through a narrow opening, the pins 26 and 24 may be removed to permit the legs to be pivoted to the dotted line position shown in Fig, 4. If desired, the telescopic struts can be locked in their elongated position by means of the pin.

Tube It comprises the lower or bottom section of a telescopic column which includes 00- axial nested tubes 34, 36. The work platform 38 is secured to the top of upper tube 36-. When the column is collapsed, access to the platform 38 may be conveniently had by means of the ladder 40 removably secured to the upper tube collar 20 by means of a pin and hole connection and seated on a telescopic strut by means of U-shaped saddles 42. A person standin on the platform 33 can readilyraise or lower the platform by actuating lever 44 which operates a pump in housing 46 to regulate fluid flow to or from the hydraulic ram to be described herein after. The worker on the platform is assured of safety by means of toe board around the periphery of the platform and. a guard rail 48 carried on the upright members 56 which are locked in their raised position by means of pins 52. The

pins 52 may be removed to permit the guard rail assembly to drop through sockets to the dotted line position shown in Fig. 2. After removal of th pump handle, the tower may be moved through a relatively low opening.

As indicated above, the telescoping and collapsing movement of the column is regulated hydraulically. Hydraulic cylinder 54 is fixed. in upper tube 36 by means of its connection to trunnion 55 which also serves as the pivot axis for sheave 58. Oil flow from the pump in housing 48 passes through flexible conduit or hose 59 into hole 62 in the upper end of the cylinder to force piston or ram 64 downwardly. Spacer tube lit is connected to the lower end of ram as by means of pin 68 which additionally serves as an anchor for cable 10. A guide and pulley block E2 is connected to the lower end of spacer tube 65 by means of bolt 14. This block is adapted to slide in the middle tube 34 to guide the lower end of the ram while serving as a support for pin '16 which rotatably mounts sheave it. As mentioned before, cable 1!! is anchored at the 10Wr end of ram B l. This cable reeved over the fixed pulley 58, passes down over pulley l2 and up to an anchor in bearing block Si; carried by middle tube 34 as illustrated in Fig. 10. Since cable :9 passes inside tube 35 on the right and between tubes 34 and 36 on the left side of pulley E8, the pulley pivot pin it is oif-center with respect to tubes to prevent chafing the cable.

Referring to Figs. and 10, it will be noted that the upper end of middle tube lid is split. Bearing and cable anchor 89 is also split. i'his construction permits manufacturing errors to be taken up simply by tightening bolts 32 to draw U-shaped clamps 34 together and close the hearing onto the upper tube. A bearing member 88 is fixed to the lower end of tube 36 to slide inside tube 34 and guide the bottom of the upper tube. The split construction permits of considerable adjustment for wear and allows use of liberal manufacturing tolerances without sac-- rificing stability.

Tube 3 5 is supported and guided in the lower tube ill. The upper end of bottom tube it split and provided with the clamps 88 adapted to draw up bearing 90 carried by tube 58. This bearing also serves as an anchor for cable 92 which is reeved over pulley 94 pivoted on pin 95 in bearing block 58 secured to the lower end of tube 34. Since cable 92 passes upwardly inside the middle tube 34 through a cooperating slot in block '52 to its anchor in bearing 86 (fixed to tube 36) the pivot pin 96 is offset as in the case of pulley pivot 16. Therefore middle tube 34 is guided by bearing 9!} and by tube bearing block 98. With this construction and with the adjustability afforded by the split tube construction described above, the tower can be maintained stable when fully extended and throughout its entire life.

When oil is pumped into the hydraulic ram, downward movement of the piston causes the cable anchor 68 and the sheave '13 to move away from the cylinder. Considering sheave E8 to be fixed in space for the moment, it will be appreciated that one inch of ram extension will cause tube 35 to rise one inch with respect to sheave '58. In order to move the ram one inch, the cable anchor 68 must move one inch, causing two inches of cable to be taken up. Now considering sheave l8 to be free, as it actually is, it will be noted that the two inches of cable necessary for the ram movement can be obtained only by raising the sheave two inches since cable la is anchored in bearing 8!]. Raising sheave "it two inches necessarily raises the upper tube 36 two inches. Therefore one inch of ram movement causes the upper tube 36 to move a total of three inches (one plus two) with respect to the middle tube 35. The same linear movement is trans mitted to the middle tube by means of cable 92 which is anchored to the upper tube at a bearing 86 and to the lower tube at bearing 90. Therefore, when the upper tube moves three inches with respect to the middle tube, the middle tube moves three inches with respect to the lower tube. It will be apparent, therefore, that one inch of ram movement results in a total of sis; inches of platform movement. In one embodiment this mechanism is used to raise the platform ten feet with only a twenty-inch ram stroke.

It will be appreciated that this lifting mecha nism provides a simple and convenient method for raising and lowering the work platform by means operated from the platform. when a worker desires to raise the platform, pump lever as is oscillated to pump oil to the hydraulic ram. The platform may be lowered by opening a conventional valve mechanism to bleed fluid from the ram to the sump through a restricted opening the size of which will determine the rate of descent. Under normal operating con ditions this mechanism provides for a. simple, rapid and quiet operation of the tower.

A telescopic air ram is provided adjacent th telescopic column and acts between the base the platform to prevent the platform from r tating on the lifting column and to retard the gravitational descent of the platform in the event the lifting mechanism should fail. The air ram is comprised of three tubular members ltd, llld the lowermost of which is secured to the lower tube collar 13 by means of laterally projecting bolts Hi6 engaging the notched uprights Hill. The upper ends of the lower tubular member HM] and of the middle tubular member in may be conveniently strapped to the telescopic column for movement therewith. The upper end of the upper tubular member is secured directly to the underside of platform 33 as illustrated in Figs. 6 and '7. The lower end of the lower tube W8 is provided with a disk valve i it adapted to seat on the centrally apertured plate H2. The lower end of the middle tubular member is provided with a plunger H4 including a rubber annulus H5 cooperating with the inside or" the lower tube Hill to form a seal. The lower end of the upper member is provided with a similar rubber annulus H8 to create an effective seal between the upper and middle tubular members. Air may by-pass this seal through central opening in regulated by a disk valve I222. The top of the upper member lil l is vented by means of a hole I24.

As the column is raised by the lifting mechanism, the tubular members comprising the air ram will telescope outwardly. he rubber seal l 45 between the middle and lower tubular members will create a partial vacuum causing air to be drawn into the lower tubular member past the disk valve Ht. Similarly, the outward movement of seal H8 with respect to the middle tube will cause air to be drawn through hole Us in the upper tube past disk valve 522 into the "Middle tube. As the platform is lowered, the pressure in the lower and middle tubes will increase, tending to seat valves H0 and H2 and compress air LL (l) in the tubes to prevent collapse of the air ram. Since the pressure is not high, the valves do not seat securely and the leakage past the valves renders the effect of the air ram substantially negligible. However, should the lifting mechanism fail, the sudden drop of the platform will increase the pressure rapidly causing the valves to seat firmly. Valves such as these are, however, subject to some leakage and this leakage permits the ram (and the platform) to descend slowly in complete safety. In practice the platform may drop freely for about six inches before the air ram takes over and lowers the platform slowly.

The utility of this tower for plant maintenance work should be apparent. In one form the platform may be raised from a low position of seven feet to a maximum height of seventeen feet in about ninety seconds. This ten-foot rise is obtainedwith a twenty-inch ram stroke. Since the guardrail may be lowered, the tower can be rolled'under relatively low overhead obstructions. The base, normally about fifty inches square, can be retracted to pass through an opening of about thirty inches. column is stable since slack in the bearings can be adjusted readily. Rotation of the platform about the axis of the cylindrical lifting column is prevented by the off-center air ram. The air ram operates upon failure of the lifting mechanism to safely lower the platform.

From the above description it will be appreciated that this tower could readily be adapted for mounting on a truck or other vehicle. A power take-oft could be employed in lieu of the manual pump when the tower is mounted on a truck.

Similarly, a motor driven pump could be em-.

ployed on the tower illustrated and described. These and other changes readily occur to those skilled in the art and are considered within the spirit of this invention. With the possibility of such changes in mind this invention is to be limited only by the scope of the claims.

We claim:

1(Telescopic apparatus comprising first, second and third tubes, hydraulic ram means having one part fixed with respect to said first tube and its other part movable with respect to said first tube, a pulley fixed with respect to said first tube, a sheave mounted on said other part of said ram means, a cable connected to said other part of; said ram means and to said second tube and reeved over said pulley and said sheave, another sheave fixed to the bottom of said second tube, another cable reeved over said other sheave and being connected to said third tube and to said Even when fully extended the first tube, and means for regulating fluid flow to and from said ram means.

2. Telescopic apparatus comprising a first tube nested within and slidable with respect to a second tube, bearing means at the upper end of said second tube and operative to guide said first tube within the second tube, hydraulic ram means mounted within said first tube and having one part fixed with respect to said first tube and its other part movable with respect thereto, a pulley fixed with respect to said first tube and said one part of said ram means, a sheave mounted on the other part of said ram means, a bearing mounted on said other part of said ram means and slidabjle within said second tube to guide said other tube, a cable connected to said other part of said ram means and to said second tube and being reeved over said pulley and said sheave, means for regulating fluid flow to and from said ram means, a third tube telescopically receiving said second tube and provided with a bearing adjacent its upper end to guide said second tube, a bearing on the lower end of said second tube and slidably engaging the interior wall of said third tube to guide the lower end of the second tube in its telescopic movements with respect to the third tube, a sheave mounted on the lower end of said second tube, and a cable connected to said third tube and said first tube and reeved over the sheave at the lower end of the second tube, extension of said ram means a given distance being operative to raise said first tube three times said distance with respect to said second tube and six times said distance with respect to said third tube.

3. Telescopic apparatus according to claim 2 in which the hydraulic ram cylinder is fixed in the upper end of said first tube.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 381,672 Brown Apr. 24, 1888 394,224 Stone Dec. 11, 1888 557,501 Ennis Mar. 31, 1896 870,998 Schapler Nov. 12, 1907 1,188,760 Hagenbusher June 27, 1916 1,337,487 Schlatter Apr. 20, 1920 1,609,437 Stimpson Dec. 7, 1926 1,735,992 Bode Nov. 19, 1929 1,917,011 Bird July 4, 1933 1,947,647 Holden Feb. 20, 1934 2,183,679 Hillis Dec. 19, 1939 2,196,511 Wagner Apr. 9, 1940 2,204,671 Erickson et a1 June 18, 1940 2,384,279 Calhoun Sept. 4, 1945

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