Elevator – industrial lift truck – or stationary lift for vehicle – Having specific load support drive-means or its control – Includes control for power source of drive-means
Reexamination Certificate
2000-01-24
2001-08-28
Salata, Jonathan (Department: 2837)
Elevator, industrial lift truck, or stationary lift for vehicle
Having specific load support drive-means or its control
Includes control for power source of drive-means
C187S227000, C414S607000, C414S912000
Reexamination Certificate
active
06279686
ABSTRACT:
The invention relates to an attachment for floor and yard trucks with a lift mast, especially for fork lift trucks, with a lift carriage which has two side plates and two horizontal beams situated one over the other with a clearance between them, on which there is held at least one hydraulically powered element from the group of load carrier “transport securing means,” rotating device, tilting device, pushing device, pulling device, holding device, lifting device, fork shifting device, lateral shift frame with the corresponding hydraulic drive, the front sides of the horizontal beams being situated in a first vertical plane and the rear edges of the side plates of the lift carriage in a third vertical plane, the said planes defining between them a space wherein the at least one hydraulic jack is arranged, which is connected with one of the horizontal beams of the lift carriage, and at least one control unit being associated with the hydraulic drive.
The subject matter of the invention can be applied advantageously in floor and yard trucks with attachments and built-in hydraulic drives, as they are described in the case of fork lift trucks in VDI Guidelines No. 3578. Accordingly, attachments are accessories which are used for picking up loads, “transport securing means,” or load transport. Such apparatus serve for picking up loads from above, in the middle and/or from the bottom, for grasping, turning, pulling and lifting the load, for tilting sideways, forward and backward, for shifting the load forward and transversely, for holding the load at the top and/or the side, and for adjusting the fork spacing.
The following are described as loads: paper rolls, concrete pipes, barrels, bales, goods packed in cartons, bricks, containers and boxes, foundry charges and bulk goods. The carrying capacity of the truck is reduced by the width, the so-called forward size, and the weight of the attachment. This requires a reduction of the said dimensions.
In the VDI Guidelines No. 3586, all materials handling equipment running on the ground (floor) which serve for the local transportation, according to their type, for the transportation, towing, pushing, lifting, stacking or shelving of loads of all kinds, which are driverless, controlled by a pedestrian or by a driver who sits or stands on the vehicle or on a driver's elevator.
Between the truck and the attachment there are provided, as a rule, so-called “interfaces” according to VDI Guidelines No. 3642. These guidelines govern the range of hydraulic pressures and delivery rates as well as the size and arrangement of hydraulic couplings. This necessarily further reduces the gross weight of the attachment and the carrying capacity of the truck and especially increases costs.
The subject matter of the invention is suitable to special advantage not only for lateral shifting systems but also for attachments and accessories according to DE 31 25 384 C2 and DE 40 41 846 A1 of the same Applicant, relating to attachments for fork lift trucks in which the forks are symmetrically shifted hydraulically transversely of their length. In the one described in DE 31 25 384 C2, the forks can also reach individually and additionally in the direction of their length, which requires additional hydraulic drives. Lateral shifting apparatus serve, of course, by the asymmetrical shifting of the load, either to compensate for driving or positioning errors or, after turning the forks by 90 degrees, for pushing the load to the left or right in storage racks. For each individual drive the required hydraulic hoses are to be provided, which ultimately results in “hose trees.”
Lateral shifting systems which are classed among the attachments are disclosed by DE 196 02 055 C1 and DE 196 02 553 A1 of the same Applicant; they are entirely hydraulically controlled through valves from the vehicle.
For this purpose the truck is connected by a corresponding number of hydraulic hoses to the lateral shifting drive, and since these hoses must permit the entire movement of the carriage they have a corresponding length and are carried in swags on pulleys, partially on the back of the mast, partially between the posts of the mast and partially also between the side plates of the lift carriage. In view of the height of the masts, which in the case of reach lift trucks can amount to six and more meters, considerable hose lengths are therefore necessary. This entails a series of disadvantages.
Pressure hoses passed around pulleys are subject to great wear. Therefore, DIN 20066, Part 5, which applies to hose lines of fluid technology, mentions that the length of time for which hose lines of this kind, including any storage time, should not exceed six years, and that the storage time itself should not exceed two years. This necessitates from time to time the replacement of the expensive pressure hoses, with all the problems of bleeding and filling up the entire hydraulic system, with the resultant costs.
Another problem is due to the possibility that in such long hoses air inclusions can develop which considerably interfere with operation because they can result in jerky movements of the lateral shifter. One can imagine a load which is situated several meters above the floor on the mast of a fork lift truck and jerking movements of the lateral shifter induce horizontal swaying.
U.S. Pat. No. 4,618,306 discloses a front-end apparatus constructed as an attachment, for tilting barrels, which consists of two hollow longitudinal beams which are rigidly connected together by a base plate. On this base plate, within a large capacity housing, there is a complete hydraulic drive system with accumulators, electric motor, hydraulic pump, oil tank and control unit. This drive system is connected only by electrical control lines to the vehicle, on the instrument panel of which the electrical control switch can be releasably fastened, but is entirely in front of the lift carriage. Due to the considerable depth of the drive unit the forks must be made accordingly longer, and the center of gravity is shifted forward a great distance toward the fork arms, so that the entire arrangement is nose-heavy. Furthermore, a jack is fastened ahead of the attachment for rotating its grabber for the barrels on one of the hollow longitudinal beams. These jacks also move the center of gravity of the attachment still further forward. To accommodate this attachment the lift forks of the truck are inserted into the hollow beams, i.e., the masses of lift forks and longitudinal beams add up with the distance of the load from the lift carriage to a considerable tipping force. The apparatus has no lateral shifting system.
DE 44 15 429 C2 discloses, in the case of an attachment with a lateral shifting system for fork lift trucks, the placement of a rotating device for finished concrete pieces on each of two lift forks. One of these rotating devices has a hydraulic drive which acts on a journal, and the other has a journal which has only an automatic return apparatus. Each of the journals has a shoe-like base body or longitudinal beam into which one of the lift forks is inserted. The hydraulic drive is connected by a quick coupling to the hydraulic system of the truck, and the hydraulic lines are carried over the lift frame. The driving system of the rotating device therefore is not self-sufficient. The reference to a rotary drive independent of the lift truck's hydraulic system says nothing about how it is housed. All of the rotary drives and their components as well as the shoe-like base bodies or longitudinal beams pushed onto the forks are all situated in front of the lift carriage. Here too the considerable structural depth of the hydraulic drive on one of the forks shifts the center of gravity very far towards the fork arms, so that the entire system is front-end heavy. In particular, this hydraulic drive shifts the center of gravity of the attachment still further forward. To receive this attachment the lift forks of the truck are inserted into the longitudinal beams of the rotary drives, i.e., even the masses o
Fulbright & Jaworski LLP
Kaup GmbH & Co. KG
Salata Jonathan
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