Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B66—HOISTING; LIFTING; HAULING
  • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
  • B66F17/00—Safety devices, e.g. for limiting or indicating lifting force
  • B66F17/003—Safety devices, e.g. for limiting or indicating lifting force for fork-lift trucks

Definitions

• weight indication for the driver so that he knows how heavy loads he handles.
• This weight indication is in accordance with the invention carried out by measuring the current to the motor of the hydraulic pump.
• a mean value of the current is taken during a certain time or this is integrated during a fixed time interval.
• Obtained values are then multiplied with a conversion factor so that the weight in for instance kg is obtained and fed to a suitable representation device that may be digital or analogous.
• the calibration weight indication may automatically control the indication in kilograms, lbs e t c.
• the weight may of course also be presented in a percentage of allowed maximum load.
• the measuring device is preferably set to zero or calibrated by measuring taking place during a lift without load. Since furthermore the inertia or rolling friction of the fork carriage e t c may vary from truck to truck calibration may as an alternative be done by lifting of a calibration weight.
• the calibration weight may be of the same size as the weights prefered to have the most correct measured value or have a slightly higher weight.
• the 0-position may be altered during use, that is in principal the current necessary for an empty lift. If desired a corresponding adjustment of the measured value can be carried out successfully since checking and comparing can be carried out by means of a small computer or microprocessor every time that an empty lift is executed.
• the weight of the load is measured during a free lift, that is the movement when the fork carriage moves in an associated extendable mast that is in its lowest position. During this movement the lifted weight associated with the truck is the lowest in relation to the load and therefor the best precision at the measuring of weight is obtained. Since it may however also be important at the lowering of a load that is situated very high up already at the lifting of this from its storing place to know its weight at least a rough weight indication may be very important. In order to achieve this compensation can be made for the weight of the lifted mast, that is the current that the engine of the hydraulic pump requires for lifting higher than the free lift without load.
• the differentiation of the measuring device between a free lift or a higher lift may easily be achieved by means of a switch or other sensor placed in the vicinity of the lower end of the mast, which switch is influenced as soon the mast is in its lowest position. When the mast is in its lowest position it is a free lift and otherwise it is a lift in which the entire mast take part.
• a switch may be used that react at the passing of the upper end of the free lift and that at each passage switch measuring mode. If lift height indication is present this can be used to deliver this information.
• the measuring device preferably during the weight evaluation controls that the movement has a constant speed. This can for instance be done by controlling the voltage the during the measurement, which voltage is to be essentially constant in order to indicate constant velocity, alternatively a compensation can take place for the acceleration.
• the constant speed at measuring is preferably chosen considerably lower than maximum speed for lifting so that the influence of hydraulic flow losses is reduced.
• the measurement in any case if a good accuracy is desired, is carried out at the same speed from measurement to measurement.
• To the weight indication may be coupled a warning signal that is activated if too big loads are on their way to be handled.
• the presentation may also indicate to which height a particular load may be lifted. Directly when the driver lifts a load from the ground or from a lorry he thus knows which is his highest permitted storage level in the ware house.
• the indication may be given directly in permitted storage levels and one can consider a programming that is also adapted to other trucks working in the ware house so that no loads get out of reach for certain trucks.
• the truck is also equipped with an additional indication or warning that indicates or warns if the maximum load is exceeded.
• the position indication may for instance be obtained in the way that is described in a simultaneously filed Swedish patent application.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Geology (AREA)
• Mechanical Engineering (AREA)
• Structural Engineering (AREA)
• Forklifts And Lifting Vehicles (AREA)
• Component Parts Of Construction Machinery (AREA)

Applications Claiming Priority (2)

Publications (3)

Family

ID=20401979

Family Applications (1)

Country Status (3)

Cited By (1)

Family Cites Families (6)

• 1996
  • 1996-03-28 SE SE9601185A patent/SE9601185L/ not_active IP Right Cessation
• 1997
  • 1997-03-26 DE DE69719232T patent/DE69719232T2/de not_active Expired - Lifetime
  • 1997-03-26 EP EP97850048A patent/EP0798261B1/de not_active Expired - Lifetime

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