Electrically driven truck In order to enable the transfer of goods on loading pallets it is known to use electrically driven trucks instead of manually operated trucks. The electrically driven trucks are however hampered by two essential drawbacks. The first drawback is the prize since also the smallest electrically driven trucks become essentially more expensive than the entirely manually propelled trucks. The second drawback is that electrically driven trucks are larger and therefor can not be manoeuvered in as limited spaces as the manually propelled ones. The step between handtrucks and electrically driven trucks is thus comparatively large and due to the greater need of space sometimes reorganizing or rebuilding may be required at a change to the use of electrically driven trucks.

As apparent from the above there exist today a need for a low cost and small electrically driven truck.

The object of the invention is to solve the above problem and provide a small electrically driven truck. This is achieved by starting from a handtruck with a tiller and support wheels in the front ends of the forks and a steerable wheel behind the forks. By a pump movement of the tiller all the wheels of the truck are displaced downward lifting the forks and the remainder of the truck upward for travel. When the load is to be put down the forks are once again lowered. Between the rear ends of the forks and the drive wheel two sides of a lifting frame extends obliquely upward and rearward to an upper fastening point of a lifting cylinder located centrally over the drive wheel. In the space between the inward and rearward extending beams of the lifting frame the mechanics connecting the front support wheels with the lifting mechanics of the steering wheel are arranged in the shape of a link system with in particular a transverse axle arranged a distance up. In accordance with the invention two essentially separate mechanical transfer systems are arranged, one on each side and with the transverse axle replaced by two axles. In this way a free space will result between the two mechanical transfer systems and between the rear ends of the forks and the steering wheel, in which space one or several batteries may be arranged.

Advantageously two batteries may be arranged on top of each other and a lid arranged over the batteries.

The drive motor with its accompanying reduction gear is then placed directly attached to the steered wheel that in this way also will be driving.

Further advantages and characteristics of the invention are apparent from the patent

claims and the following description of a preferred embodiment that is also shown in the enclosed drawings. Here fig. 1 shows a truck in accordance with the invention seen from the side, fig 2 the same truck seen from above and fig 3 the truck from behind.

The truck shown in the drawings includes like ordinary handtrucks two forks 1, which in their rear ends are connected with a transverse beam and two obliquely upward, rearward and inward extending beams 2 connected in their upper ends by a cupola like part 3 for the reception of the piston rod of a lifting cylinder 4, while the lifting cylinder in the lower end is fastened to a pressure plate 5 connected to a steering wheel 6. On this pressure plate the pump cylinder of the hydraulic system is fastened, which can be acted upon by a tiller of the truck journaled in the lifting cylinder for pivot movement up and down.

In the front end of the lifting forks support rollers 7 are arranged on arms 8 that can be transferred between a lowered load lifting position and a lifted load freeing position. The transition is by means of rods 20 that in turn are connected to arms 9 journaled in the rear end of the truck in the frame of this on two axles 19, one on each side. One arm 9 is placed on each side of the truck. These rear arms 9 are then pivot journaled in essentially vertical fork-or leglike downward extending extension parts 10 that extend downward from a pivot bearing unit 17 in which a steering axle is journaled connecting the pressure plate 5 with the support wheel 6. In this way the arms 9 are coupled to the lower end of the lifting cylinder, that is the end that displaces the steered support wheel in the rear end of the truck downward at lifting. In this way a lifting movement of the lifting cylinder 4 will not only displace the rear support wheel downward but synchronously with this also the front support wheels will be displaced downward so that the desired parallel lifting of the forks of the truck is achieved.

The arms 9 at the same time serve as a guide for the pivot bearing unit and thereby the driving and steering wheel 6.

Between the lower ends of the inclined upward, inward extending lift frame beams and between the bearings of the arms 9 two batteries 11 are arranged on each other and in front of and above the batteries an essentially triangular hood panel with triangular side panels is arranged. The hood joins in the upper end an horizontal panel 13 where a battery separator 14 is arranged as well as a connection 15 for electricity from the electricity supply network while charging.

The truck is advantageously provided with an own charging means so that the only thing required is a flexible cord. Advantageously the battery separator 14 is so arranged that it can not be switched to its ON-position unless a possibly connected charge flexible cord

from the mains supply has been removed. In this way the risk of forgetting the removal of the flexible cord when the truck is to be used is eliminated.

Since the truck includes its own charging device it can be connected at different locations and one can also consider the truck being charged from the net as well as from the electric system of for instance a lorry.

The steering wheel 6 is provided with an electric motor for driving via a reduction gear. Motor, gearbox and wheel journaling are built together to an integrated drive unit 16 that via an electronic control circuit is connected to the batteries 11. Advantageously also the control circuit of the motor is integrated in the drive unit 16. The drive unit 16 is connected to the pressure plate 5 via the steering axle of the support wheel 6 and pivotable by means of the tiller 18 in a known manner.

In the tiller handle, as in other electrically driven trucks a so called belly button is arranged, that is a security button that switch off the truck when the button is depressed, for instance if the handle push the driver against a wall. Furthermore in the handle two buttons are arranged actuatable with one or the other thumb. One button provides drive rearward while the other provide drive forward. Through a double depressing of one of the buttons a higher drive speed is obtained, that for instance may be the double speed as compared to the speed that is obtained if the button is depressed only once directly. As soon as the button is released the driving stops. In order to obtain the double speed the double depression has to take place within a relatively defined interval of time so that possible contact bounces or the like do not result in erroneous instructions to the truck. Furthermore slower driving than at only depressing the button once can be obtained by intermittent activation of the drive motor with the lower speed at positioning.

In a conventional way the truck is provided with actuation means for pumping up and lowering of the load forks as well as a brake etc.

Since the batteries are small the cost for these is small and even if this means that the usable drive time becomes comparatively small this is in the normal case no problem since these truck seen totally are not driven long stretches. Since the truck furthermore brings its own charging device along it can easily be connected in different places and be charged between the times of use. Since the batteries are possible to arrange between the beams of the lifting frame and the steering wheel the length of the truck is not increased, not lengthwise nor diagonally in relation to an ordinary handtruck. Therefor a trained user need not to relearn in order to handle the length of the truck but can use this electrified truck in

precisely the same way as a handtruck without motor and with just as much mobility.

Through the placing of the batteries furthermore the possibility to retain the inclined sides of the truck is obtained, which contributes to the ease with which one can pass closely to the truck and the risk of getting bruises from protruding corners is diminished. Furthermore the truck almost looks like an ordinary handtruck due to this.

Since the lifting is manual the batteries need not to be dimensioned for the high current loads that are required at electrically driven lifting pumps but are only used for moving and therefor last longer than otherwise would have been the case, It can be mentioned that the retaining of the original look of the handtruck when it comes to the frame has strength advantages since it is very strong in relation to its weight.

As soon as the truck is made more box like in the transition between forks and lifting part for the reception of batteries the additional use of material and increase in weight becomes considerable if one wish to retain the same load capacity.