POSITIVE LOCK MECHANISM FOR MOVING BOARD

Abstract: Positive lock mechanism for use with a moving board (1) to move an object (29) up or down stairs (31) by sliding such moving board (1) over the crests of the stairs (31). The positive lock mechanism comprises a shaft (11), spade element (15) and torsion spring (17). The moving board (1) freely mounts the shaft (11) which carries the spade element (15) and torsion spring (17). The torsion spring (17) biases the spade element (15) to a retractable positive lock position for engagement with a stair tread (33) whereby the moving board (1) and its load (29) can remain in a free standing position of rest on the stairs (31). The moving board (1) may be slid up or down over the crests of several steps before the spade element (15) is allowed to engage a stair tread (33) in positive lock position, or the movers may take one step at a time by allowing the spade element (15) to engage each step successively.

Description: Description Positive Lock Mechanism For Moving Board Technical Field This invention relates to a positive lock mechanism for use with a moving board or piano board for use in sliding a heavy object or piano up or down over the crests of a flight of stairs, and such that during such sliding procedure the positive lock mechanism automatically allows the moving board with its load to be rested "free stand¬ ing" at any or all steps without the intervention or ap¬ plication of any force on the part of the movers to hold the load on the stairs. Background Art The prior art, U.S. Patent No. 1,164,332, discloses a piano truck; U.S. Patent No. 1,714,352 discloses a water ski; U.S. Patent No. 2,347,441 discloses a ski; U.S. Pat- ent No. 2,456,002 discloses a ski brake; U.S. Patent No. 3,015,123 discloses a vacuum cleaner with wheeled under¬ carriage; U.S. Patent No. 4,130,291 discloses a shopping cart capable for use on stairs; U.S. Patent No. 4,504,071 discloses a two wheeled utility cart; and German Patent No. 347441 discloses a device for advancing a carriage over staircases. Disclosure of Invention A piano board is utilized to move a piano up or down a flight of stairs by sliding the runners of such piano board over the crests of the stairs. This not only entails exhausting work effort on the part of the piano movers, but also introduces a safety problem. Inasmuch as a piano has considerable weight and inasmuch as the piano is slid¬ ing, via the piano board, either up or down the stairs, there remains the ever present danger of the piano movers losing control of the load and crushing or otherwise in¬ juring the piano mover below, as well as damaging the pi¬ ano. Hence, there is a need for a positive lock mechanism for the piano board whereby the piano board, whether in ascent or descent, can be stopped at any or all steps in a state of rest in free standing positive lock position to give the piano movers a chance to rest or for whatever purpose. The object of the invention is to provide a posi¬ tive lock mechanism comprising a spade element depending from the piano board and fixedly carried by a cross shaft mounted in bearing relationship by and between runners which depend from the platform of such piano board. A tor¬ sion spring, carried on the cross shaft, biases the de¬ pending spade element into its positive lock position such that the spade element engages a stair tread. In such pos¬ itive lock position of the spade element engaging a stair tread, the piano board with a piano loaded thereon remains at rest in free standing position on the stairs. Brief Description of Drawings This object and other objects of the invention should be discerned and appreciated by reference to the drawings, wherein like reference numerals apply to similar parts throughout the several views, in which: Fig. 1 is a side elevation of the invention in its as¬ cent position; Fig. 2 is a perspective view of the inven¬ tion; Fig. 3 is a sectional view taken along the line and in the direction of the arrows 3-3 in Fig. 1; Fig. 4 is a sectional view taken along the line and in the direction of the arrows 4-4 in Fig. 3. Best Mode for Carrying Out the Invention In Fig. 1 of the drawings, reference numeral 1 general- ly refers to the invention of the moving board with its positive lock mechanism. The moving board is shown as a sled-type piano board having a flat platform 3 with an upstanding foot 5 at one end. Platform 3 and foot 5 are covered by appropriate padding 7. Fixedly depending from platform 3 are longitudinal runners 9. Appropriately car¬ ried in transverse relationship with runners 9 is a cross shaft 11 freely received by bearings 13 carried by a de¬ pending spade element 15. A torsion spring 17, operatively mounted on cross shaft 11, has tails 19 and 21 in abutting relationship with and operative engagement against the lower surface 23 of platform 3 and against spade element 15, and thereby constrains rotation of spade element 15 in a clockwise direction, as viewed in Figs. 1, 2 and 4. As shown in Fig. 4, lower surface 21 of platform 3 func- tions as a limit stop to prevent further clockwise rota¬ tion of spade element 15. Spacer washers 25, carried on cross shaft 11, are interposed between the runners 9 and spade element 15, as shown. Rope handles 27 are provided on the lateral sides of the runners 9. In Fig. 1, an object 29 is shown on the piano board for ascent of the flight of stairs 31. The object 29, such as a piano, is appropriately secured to the piano board such as by stapping or lashing same thereto. Spade element 15 is shown in its positive lock position engaged with a stair tread 33. In such positive lock position, the pi¬ ano board can remain free standing on the stairs 31 with¬ out the attention or intervention of the piano movers. In ascent, the runners 9 are slid upward a sufficient distance over the crests of the stairs 31 (i.e., the ex¬ ternal junction of the treads 33 and risers 35) such that spade element 15 can engage the next higher tread 33. In sliding the runners 9 upwardly over the stair crests, ris¬ er 35 and then the next higher crest will engage such spade element 15 and cause same to rotate counterclockwise to its retracted position, as indicated by the phantom lines 37 in Fig. 4. When spade element 15 passes beyond such next higher crest, the restoring force of the torsion spring 17 will cause spade element 15 to rotate clockwise; and, when the runners 9 have been slid upwardly over the crests a further distance, spade element 15 will rotate clockwise to its furthest extent to its positive lock po¬ sition and will be engaged with the next higher stair tread 33. Spade element 15 is appropriately padded (not shown) to prevent same from digging into or otherwise dam¬ aging the stairs 31. In descent, with the piano or object 29 secured to the piano board, the piano board with its secured object 29 is placed at the top of the stairs 31 and is cantilevered over the top-most step until the runners 9 lie upon the crests of the stairs 31. The runners 9 will slide downward until spade element 15 engages a stair tread 33 in posi¬ tive lock position. In such positive lock position, the piano board will remain free standing on the stairs 31 without attention or intervention on the part of the piano movers. To resume sliding the runners 9 downward over the crests of the stairs 31, the piano board is pushed upwards a sufficient distance to free spade element 15 from en- gagement with such stair tread 33 and to allow spade ele¬ ment 15 to clear tread 33 in order to rotate spade element 15 counterclockwise to its retracted position 37 by appro¬ priately pulling lanyard 39 carried by spade element 15. Thereupon, the piano movers have the choice of sliding the piano board downward one step or several steps before lanyard 39 is released to allow spade element 15 to rotate clockwise to its positive lock position to engage a stair tread 33.

Claims: Claims 1. A piano board for carrying a piano and for use in slid¬ ing said piano, either in ascent or descent, over the crests of a flight of stairs with said piano board hav¬ ing a depending spade element to automatically allow said piano board to be rested free-standing, whether in such ascent or descent, at any one or all of the steps of said flight of stairs without the intervention or application of force on the part of any human opera¬ tor to physically hold said piano board with its piano carried thereon in its rested position on the stairs; said piano board comprising a flat platform, foot, lon¬ gitudinal runners, cross shaft, depending spade ele¬ ment, torsion spring and lanyard; said piano board be¬ ing of the sled type and having said flat platform, said flat platform having a lower surface, said flat platform having terminal ends, said foot being upstand¬ ing from one of said terminal ends of said flat plat¬ form, said longitudinal runners depending from said platform, said runners freely carrying said cross shaft in transverse relationship therewith, said spade ele¬ ment having proximal and distal ends, said cross shaft freely mounting thereon said spade element in pivotal relationship between its said proximal and distal ends with said spade element thereby functioning as a first order lever, said cross shaft freely mounting thereon said torsion spring, said torsion spring having tails at its remote ends, said spring tails being in abutting relationship against and operative engagement with said lower surface of said flat platform and said spade ele- ment to constrain said spade element to rotate in one direction, said lower surface of said flat platform functioning as a limit stop to prevent further con¬ strained rotation of said spade element upon said prox¬ imal end of said spade element abutting said lower sur- face of said flat platform, said lanyard being opera¬ tively connected to said spade element and, upon said lanyard being pulled sufficiently by a human operator and held as pulled, said spade element being caused to rotate to its retracted position between and within said longitudinal runners; upon ascent of said piano board over a flight of stairs: said runners sliding upwardly upon and over the crests of said flight of stairs, and the step riser before the next higher crest and said next higher crest, engageable by said spade element, engaging said spade element and causing said spade element to rotate in one direction towards its retracted position, and, upon said spade element pass- ing beyond said next higher crest, the restoring force of said spring causing said spade element to rotate in the direction opposite to its retracted position to its position of automatic engagement and positive lock with said distal end of said spade element engag- ing the stair tread after said next higher crest and with said proximal end of said spade element abutting said lower surface of said flat platform; and upon de¬ scent of said piano board over a flight of stairs: said lanyard being pulled sufficiently by a human operator and being held as pulled to cause said spade element to be rotated to its said retracted position, and said runners sliding downwardly upon and over the crests of said flight of stairs to the next lower step engage¬ able by said spade element, and, upon said lanyard be- ing manually released by the human operator, the re¬ storing force of said spring automatically causing said spade element to rotate to its position of automatic engagement and positive lock with said distal end of said spade element engaging the stair tread of said next lower step with said proximal end of said spade element abutting said lower surface of said flat plat¬ form. 2. A piano board as defined in claim 1, wherein said run¬ ners have lateral sides, wherein are further provided handles and wherein said lateral sides carry said han¬ dles.

Inventors: POTTER ROGER A, POTTER, ROGER, A.
Applicants: POTTER ROGER A, POTTER, ROGER, A.
Application year: 1986
Main classification: B62B5
IPC codes: B62B5