GB2183566A

GB2183566A - Wagon with caster wheels

Info

Publication number: GB2183566A
Application number: GB08627412A
Authority: GB
Inventors: Hiroshi Mizuno; Kenji Okiyama; Yoshiaki Takasuki
Original assignee: Yoshida Kogyo KK
Current assignee: YKK Corp
Priority date: 1985-11-18
Filing date: 1986-11-17
Publication date: 1987-06-10
Also published as: IT8667850A0; AU6516386A; IT8654094V0; GB8627412D0; FR2592341A1; DE3639069A1; JPS6283792U

Abstract

A wagon having a pair of drive wheels (4a,b), a pair of front casters (2a,b) and a pair of rear casters (3a,b) is disclosed. A pair of support members (7a,b) extending parallel to the direction of travel each have an intermediate portion pivotably mounted on the lower surface of a deck (1). Each of the pair of front or rear casters (2,3a,b) and each of the drive wheels (4a,b) are coupled to the opposite ends of each support member (7a,b). Each drive wheel (4a,b) is driven independently by each drive unit (8a,b). The arrangement facilitate the negotiation of bumps without losing traction of the drive wheels. <IMAGE>

Description

SPECIFICATION Wagon This invention relates to a wagon which is used for transporting products and other goods in the premises of a factory, a warehouse, etc., and more particularly, to a mechanism for mounting drive wheels and driven wheels on a deck or body.

In a priorartwagon usedfortransporting goods in the premises of a factory, a warehouse, etc., usually eitherfrontorrearwheelsamongthefourwheels provided on a deck are drive wheels, and the other wheels are adapted to be directed in desired directions by handle operation. In the wagon having the above construction, revolution in a narrow place is very troublesome, and the wagon thus lacks manoeuverability.

To solve the above problems, a wagon having casters has been developed. Japanese Utility Model Publication No. 58-8620 discloses a wagon, in which casters are provided atthefourcorners ofthe lower surface of a deck, a rockable horizontal rotor is assembled in a central portion ofthe lower surface of the deck, an axle is secured to the horizontal rotor, opposite side drive wheels are mounted on the axle such thattheyface each other, and drive mechanisms are provided for controlling the forward and backward driving of the two drive wheels independently. By using casters as wheels other than the drive wheels, revolution in a narrow place or passage can be readily obtained, and sufficient manoeuverability can be obtained.

However, in the prior art wagon with casters, as schematically shown in Figure 1,thefrontand rear casters 2 and 3 and drive wheels 4 are all installed at fixed positions on the lower surface of the deck 1.

Therefore, in the prior art wagon, if an obstacle S is encountered on the running ground Gas shown in Figure 1, afrontcaster2will ride on the obstacle so that the wagon body is floated. Consequently, the drive wheels 4 are raised, so that a distance is produced between the drive wheels 4and running ground G. In such d case, the drive wheels idle, and thewagon can no longer run. The same situation occurs when a rear caster3 rides on an obstacle S.

According to the present invention there is provided a wagon comprising a deck, a pair of front casters and a pair of rear casters provided underneath said deck, a pair of drive wheels each provided intermediate and parallel to the associated front and rear casters, and at least two support members extending parallel to a normal direction of travel and each having an intermediate portion pivotably mounted underneath said deck, each of said pair of front casters or said rear casters and each of said drive wheels being coupled to opposite ends of at least one respective said support member, the other pair of casters than those coupled to said support members being mounted to the lower su rface of sa id deck.

It is believed possible by means ofthe present invention to provide a wagon, in which the drive wheels are reliably in contact with the ground surface so that it can be run even when either caster happens two ride on an obstaclewhile itis running on a non-leveled ground with obstacles and irregularities.

It isfurther believed possible by means ofthe present invention to provide a wagon, which is capable of ready revolution even in a narrow place ora passage, has sufficient manoeuverability and can run on a non-leveled ground with obstacles and irregularities by positively riding on obstacles or irregularities against resistance offered by them.

The invention will be described by way of example with reference to the accompanying drawings, wherein like references referto like parts unless the context requires otherwise and wherein Figure 1 is a schematic side view showing a prior art wagon with casters in a state happened to ride on an obstacle; Figure2 is a side view showing an embodiment of the wagon according to the invention; Figure 3 is a bottom view showing a wagon shown in Figure 2; and Figures4and 5aresideviewsshowingthewagon of Figures 2 and 3 in respective states as a result of having ridden onto obstacles.

Now, a preferred embodiment of the invention will be described with reference to the accompanying drawings.

Referring to Figures 2 and 3, a pair of front casters 2a and 2b are installed symmetrically at the front corners of the lower surface of the deck 1 such thatthey are capable of revolution in a oscillating fashion so thattheycan proceed in anydirection.Apairof brackets 5a and 5b are provided on opposite side portions of the lower surface of the deck 1 rearwardly of the center of the deck. Shafts 6a and 6b are provided in the brackets 5a and 5b so as to extend at right angles to the direction of travel (to the left in the Figures). Two pairs of support members 7a and 7b are respectively mounted oscillatably on these shafts 6a and 6b.The pairs of support members 7a and 7b each consist of two V-shaped elbow-likeflat plates, between which a rear caster 3a/3b and a drive wheel 4a/4b are mounted. Each support member may be straight, instead of V-shaped. Drive wheels 4a and 4b are provided at the front ends of the support members7a and 7b, and rearcasters3a and 3b are prov- ided at the rear ends. The rear casters 3a and 3b, like thefrontcasters2a and 2b, are installed suchthat they are capable of revolution in an oscillating fashion in any direction.The shafts 6a and 6b are mounted at positions spaced apart fro the center of thesupport members7a and 7b such thattheirdis- tances from the drive wheels 4a and 4b issmaller than theirdistancesfrom the rear casters 3a and 3b.

Motors 8a and 8b are secured to lower portions of substantially central portions of the support members 7a and 7b. Their output shafts 9a and 9b are coupled to the drive wheels 4a and 4b via pulleys 1 Oa and i0bsecurndtotheshafts9a and Sb, beltslla and 11 b and pulleys 13a and 13b securedtothe shafts 1 2a and 1 2b of the drive wheels 4a and 4b, and the drive wheels 4a and 4b are driven independently.

As drive units, ordinary drive means such as those based on motors or internal combustion engines may be used.

A control box 14 is provided on top of the deck lIt accommodates a control unitfor controlling the drive units.

In this embodiment the two shafts 6a and 6b are provided at opposite sides. However, these shafts may be replaced with a single shaft. Further,thesup- port members may be provided between the drive wheels and front casters or between the drive wheels and rearcasters. Further, itis possible to arrangethe two support members differently, i.e., one being between drive wheel and front caster and the other being between drive wheel and rear caster. Further, itis possibleto couplethe individual drive unitsand drive wheels using other well-known powertransmission mechanisms such as chains.

The wagon described above can be steered in a desired direction by accelerating or decelerating one of the motors or by varying the revolving rate of one of the drive wheels through braking thereof.

Thewagon may be eitheran automaticallyorman- uallyoperablewagon. Inthecaseoftheautomatic- ally operable wagon, a guide zone provided on a road surface, for instance, may be detected with well-known detection means, and the detection signal may be used for direction control. (For example, referto Japanese Patent Publication No.55- 12605.) In the case of Figure 1,the ground surface G is flat.

When front caster 2a comes to ride on an obstacle S (e.g. a stone) during running of the wagon as shown in Figure 4, a front portion of the deck 1 is displaced upwardly. Atthistime, the rear portion of the deck 1 is tilted downwardly because of the weight of the deck itself (and supported goods if any). Thus, the rear casters 3a are tilted upwardly by the reaction force with respectto the ground, while the same timethesupportmember7a is pivoted in the counterclockwise direction about the shaft 6a, so that the drive wheel 4a is positively brought into contactwith the ground.

When a rearcaster3a strikes and rides on an ob stacle Sasshown in Figure5,thesupportmember7a is pivoted in the counterclockwise direction about the shaft 6a. Again in this case, the drive wheel 4a is positively brought into contact with the ground. It is to be understood that even if a caster rides on an obstacle, no drive wheel is caused to float in consequence, but all the drive wheels are held in contact with the ground sothatthewagon can be reliably run continually.

Further, where the position of support ofthe support members is shifted toward the position ofsup- port of the drive wheels, when the rear caster3a rides on an obstacle Sin case of Figure 5, an upward force acts on the support member7a to enhance the contactforce of the drive wheel 4a with respect to the ground by a lever action. Thus, even when the wagon encounters a non-leveled ground having obstacles and irregularities and receives resistance againstrunning,itcan positively run on the nonleveled ground againstthe resistance offered by the obstacles and irregularities.

While the representative embodiment and details have been shown for the purpose of illustrating the present invention, it will be apparent to those skilled in the art that various changes a nd modifications may be made therein without departing from the spirit or scope of the invention.

Claims

1. Awagon comprising a deck, a pairoffrontcasters and a pair of rear casters provided underneath said deck, a pair of drive wheels each provided intermediate and parallel to the associated front and rear casters, and at least two support members extending parallel to a normal direction of travel and each having an intermediate portion pivotably mounted underneath said deck, each of said pair offront casters or said rear casters and each of said drive wheels being coupled to opposite ends of at least one respective said support member, the other pair of cas tersthan those coupled to said supportmembers being mounted to the lower surface of said deck.

2. Awagon according to claim 1, wherein the position of coupling ofsaid support members to said deck is shifted toward the position of coupling of said drive wheels.

3. A wagon according to claim 1 or 2, wherein said support members are V-shaped.

4. Awagon according to claim 1,2or3,wherein said pair of drive wheels and said pair of rear casters are coupledto one another bysaid supportmembers.

5. Awagon accordingto any preceding claim, which further comprises a pair of derive units secured to lower portions of substantially central portions of said support members, said pair of drive wheels being driven independently by said respective drive units.