United States Patent 3724864

A combination hand truck and a manual or power driven propulsion unit including means for removably securing the propulsion unit to the body of the hand truck. The hand truck is of conventional type wherein the body is preferably, though not restrictively, made of metal tubing or the like, supported by two forward ground-engaging wheels.

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International Classes:
B62B5/02; (IPC1-7): B62B5/02
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US Patent References:
3142351Stair climbing wheelchair1964-07-28Green
3133742Stairclimbing wheelchair1964-05-19Richison et al.
2763489Hand truck provided with track type treads1956-09-18Marsalis

Primary Examiner:
Friaglia, Leo
What I claim is

1. In an appliance hand truck having an elongated main frame supported at its forward end by ground engaging wheels; the improvement comprising a traction unit including parallel frame members of inverted channel section,

The present invention relates to improvements in hand trucks and in particular to a type of hand truck used for conveying heavy loads such as appliances and the like up and over inclined irregular surfaces such as flights of stairs, curbings and the like.

The objects of the invention are:

To provide and improved hand truck of the character described which includes a propulsion unit in the form of a base structure adapted for ready securement to or removal from the body of a conventional hand truck and wherein said base structure comprises downwardly opening parallel channel members with elongated bars or plates, sometimes hereinafter referred to as "walking beams," mounted within the channel members for independent reciprocal motion relative to each other.

To so form the exposed bottom edges of the blades as to simulate the general appearance and characteristics of saw-teeth so far as the shape thereof is concerned, but not the cutting action.

To provide a heavy-duty hand truck provided with a strong, durable and efficient propulsion unit which is so constructed as to present a minimum amount of friction, making possible manual operation by a single operator.

The foregoing and other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawing forming a part hereof, and in which:

FIG. 1 is a perspective view of a hand truck combined with a traction unit made in accordance with my invention,

FIG. 2 is a perspective view of a bearing bracket,

FIG. 3 is a perspective view of a cam shaft showing cam members secured to the shaft near the opposite ends thereof,

FIG. 4 is a perspective view of one of two identical inverted channel members,

FIGS. 5 and 6 are perspective views of two identical bars or plates operatively supported at both of their ends by the cam members shown in FIG. 3 and operable as walking beams with their bottom edges having the characteristics of saw teeth,

FIG. 7 is a sectional elevational view on an enlarged scale taken approximately along the line 7-7 of FIG. 1, and

FIG. 8 is a fragmentary view on a reduced scale illustrating in full and broken lines the progressive stepping or crawling action of the walking beams illustrated in FIG. 5 and 6 and in alternate increments of advancement in stair climbing operation.

With continuing reference to the drawing wherein like reference numerals indicate like parts, the hand truck frame indicated generally by numeral 1 comprises two vertically disposed side frame members indicated generally at 2 and 3 permanently secured in parallel relation to each other by transverse tubular members 4 and by a transverse load carrier 5 at its forward end and a cross plate 37 at its rearward end. The top and bottom rails 7 and 8 respectively of each side frame member are reinforced in their parallel relation to each other by tubular members 11. The forward end of the hand truck body 1 is supported in any suitable manner by ground engaging idling wheels 9.

A traction unit indicated generally at 12 is secured at its forward end as by welding or the like to the underside of the truck body 1. The unit comprises two identical parallel downwardly opening channel sections 13 and 14 fixedly secured to the underside of the truck body 1 by vertical tubular members 15 and 16. The bottom ends of these tubular members 15-16 are similarly secured to the web 17 of the channel members 13-14. The forward and rearward ends of the channel members 13-14 (FIG. 4) are provided with transversely aligned forward sleeve bearings 18 and rearward sleeve bearings 19. Since both channel sections and their internal and external related parts are identical a description of the one channel section assembly will suffice for both.

A driven shaft 20 is journaled in the transversely aligned forward sleeve bearings 18 of both channel members 13-14 and extends outwardly therefrom. Either or both of the extended ends of the shaft 20 is provided with a driven sprocket wheel 21.

Two identical pairs of diametrically opposed cam members 22-23 are secured in any suitable manner to the forward driven shaft 20 inwardly from the ends thereof for driving rotation within identical roller bearings 24-24 at the forward end of the two identical walking beams 26-27 within the channel member 13. On the opposite end of shaft 20 the other pair of cam members 22-23 are similarly functional in roller bearings (not shown) in the corresponding end of the companion channel member 14.

As best illustrated in FIGS. 1 and 7 the rearward driving shaft 30 is provided with a bevel gear 31 enmeshed at all times with a companion bevel gear 32 secured to the rearward end of a crankshaft 33 journaled near its rearward end in a bearing 34 extending downwardly from the cross plate 6 secured in any suitable manner to the forward end of the webs 17 of the channel members 13 and 14. The shaft 33 extends rearwardly through a sleeve bearing 36 depending from a second cross member 37 welded or otherwise secured at its ends to the bottom rails 8 of the truck body frame 1. This end of the shaft 33 terminates in a crank handle 38.

A sprocket chain 40 is entrained over both sprocket wheels 21 to impart rotation to the cam members 22-23 within their respective roller bearings 24-24 to thereby impart (FIG. 8) reciprocal rotary convolutions 42-43 to the walking beams 26-27 to cause intermittent progressive gripping engagement of the "saw tooth" bottom edges of the walking beams 26-27 with the edges of the steps 44.