1.  Field of the Invention
This invention relates to a fork lift truck with a chassis and a battery block that can be positioned inside the chassis.  The chassis has a lateral opening so that the battery block can be removed essentially in a horizontal, e.g., lateral, direction. 
2.  Technical Considerations
An electrically-powered fork lift truck of the general type described above is typically equipped with a battery block that contains storage batteries and provides the energy required for the traction drive system, the lifting drive system, and the other electrical units of the truck.  To make it possible to replace the battery block, for example if it becomes damaged, the chassis of the fork lift truck is configured so that the battery block can be removed and a new battery block can be inserted by means of a suitable conveyor device.  The battery block must typically be replaced frequently when the fork lift truck is used in multiple-shift operations.  In that case, a discharged battery block in the fork lift truck is replaced regularly by a freshly charged battery block. 
The chassis of some fork lift trucks is designed so that the battery block can be removed upwardly by a crane.  One disadvantage of this arrangement is that the components that are located above the battery block, generally the driver's cab and the protective roof over the driver, must be able to pivot at least to some extent to make it possible to hoist the battery block. 
On fork lift trucks that have a lateral opening for the removal of the battery, a roller conveyor can be located inside the fork lift truck on the floor of the battery compartment.  Using this roller conveyor, which is permanently installed inside the fork lift truck, the battery block can be pushed in the horizontal (i.e., lateral) direction onto an external roller conveyor that is located next to the fork lift truck.  To provide the chassis of the fork lift truck with the required rigidity in spite of the large lateral opening for the battery block, it is known that a structural section that runs underneath and alongside the opening can be provided to support the weight of the battery block.  A fork lift truck of this type is described in DE 100 05 285 A1, for example.  One disadvantage of this arrangement is that the roller conveyors are absolutely essential to change the battery. 
Therefore, it is an object of this invention to design a fork lift truck so that a pallet truck, for example, can be placed underneath the battery block located in the fork lift truck and the battery block can be lifted and removed through the lateral opening of the chassis without the need for a permanently mounted conveyor in the truck.