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
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01G—WEIGHING
  • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
  • G01G19/08—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for incorporation in vehicles
  • G01G19/083—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for incorporation in vehicles lift truck scale

Definitions

• This invention relates to a vehicle of the type having ground engaging wheels such as road wheels or wheels for guiding/driving tracks, and means to sense a load sudh as the weight of the vehicle transmitted through a load carrying part, to the ground engaging wheels.
• ground engaging wheels such as road wheels or wheels for guiding/driving tracks
• Such vehicle will hereinafter be referred to as being "of the kind specified”.
• the load sensing means is mounted at a position closer to the ground engaging wheels than to a central longitudinal axis of the vehicle.
• the or each load sensing means comprises a load cell which provides a structural connection between the axle and a hub mounted on the axle so that the load is transmitted through the cell to the hub.
• the invention is particularly applicable to a vehicle having an oscillating axle wherein the connection between the axle and a body of the vehicle is by means of a single load pin which permits the axle to oscillate in response to the terrain over which the vehicle is travelling.
• axle for a vehicle according to the first or second aspect of the invention, the axle including a load sensing means to determine the weight transmitted from the axle to the ground.
• FIGURE 1 is a side illustrative view of a vehicle which may incorporate the invention
• FIGURE 2 is a side view shown partly in section of the steering axle of Figure 1;
• FIGURE 3 is a plan view of the axle of Figure 2;
• FIGURE 4 is an enlarged view of the cross sectioned part of the axle of Figure 2.
• a vehicle 10 which may embody the invention comprises a loading vehicle which has a loading arm 11 mounted on a body 12 for movement about an axis 13, by hydraulic actuators 14.
• the body has two pairs of ground engaging wheels 15 and 16, the rear pair 16 being movable to steer the vehicle, whilst wheels 15 are fixed.
• An operator may drive the vehicle 10 and operate the actuators 14 from a cab 18.
• the loading arm 11 in this example is of the telescopic type having a base part 19 which is fixed relative to the pivot 13, and a telescoping part 20 which can be telescoped by hydraulic actuators with the base part 19 (not shown), the telescoping part 20 carrying at its outermost end, loading forks 21.
• any desired implement such as a bucket for example could be provided as an alternative to the loading forks 21.
• Such a loading arm 11 is able to lift loads to a considerable height relative to the vehicle body 12 and by extending the telescoping part 20 forwardly, loads can be moved a considerable distance from the vehicle body 12.
• the loading forks 21 can be moved relative to the telescoping part 20 about a pivot axis 17 by a further actuator 22, again operated from the operator's cab 18, and/or operated automatically as the boom 11 is lifted and lowered to maintain the forks 21 in a level attitude as shown.
• the vehicle has to be particularly designed to provide maximum stability in a fore and aft direction over the entire working range of the arm 11 for a maximum specified load.
• the vehicle 10 may become unstable, at least when the load is moved out beyond a safe limit, as the telescoping Dart 20 for example is telescoped forwardly.
• a safe load indicator to provide a warning to the operator when, for example, a load is moved out in the direction of arrow A in figure 1 of the drawings, relative to the body 12, beyond a safe limit.
• the vehicle 10 has a rigid rear axle 23 (see figures 2 to 4) carrying wheels 16 on hubs 30.
• the axle 23 is pivoted to the body 12 for pivoting about a single central pivot axis 25 as is conventional.
• strain gauges it has been usual practice for strain gauges to be provided on the pin. Using these strain gauges, the weight of the vehicle on the rear axle 23 transmitted via the pin, can be determined, to give an indication to the operator as to how movement of the load is changing the balance of the vehicle.
• strain gauges are not used on a load pin at the pivot axis 25, but rather, in this example, a pair of load cells 26 are used one at each of the opposite ends of the axle 23, at positions spaced outwardly of the axis 25, adjacent each hub 30 provided for wheels 16.
• each end of the axle 23 is substantially identical, but oppositely handed, and hence only a detailed description of the end of the axle 23 shown in fragmentary cross section in figure 2 will be described in detail.
• the axle 23 is a powered axle, having a housing 27 for a crown wheel and gear, which is connected at 28 via a suitable transmission to an engine of the vehicle 10.
• half shafts (not shown) each extend to a hub 30 at each end via a universal joint 31, so that an outer wheel receiving part 30a of the hub 30 may be driven, via a constant velocity joint mounted within the hub 30.
• the hub 30 also contains brakes as is conventional although alternatively, brakes could be provided to brake the half-shafts, again as is conventional.
• the axle 23 is connected to the vehicle body 12 by a load pin which is received in a pivot boss 33 so that the axle 23 may oscillate about an axis 25 although as will become apparent hereinafter, other types of axle can be used as required.
• Each hub 30 may be moved about a generally upright axis 34 for steering, the hubs 30 at each end of the axle 23 being connected to a steering bar 35 which may be moved by a rack and pinion mechanism, or by hydraulic actuators as required, under the control of the operator.
• the hub 30 comprises a pair of spaced bearing mounting parts 36 which receive between them the axle end 37 which is of channel-like configuration, the opening of the channel in use, receiving the universal joint 31 which is not shown.
• the limbs of the channel end 37 each present outwardly extending cups 38, and load cells 26 are disposed in the cups 38 between the limbs of the channel axle end 37 and bearing mounting parts 36 of the hub 30.
• the ends of the axle 23 may have mutually inwardly facing cups to receive the load cells with the load cells 26 being movable with the hubs 30.
• the bearing mounting parts 36 each have a retaining cap 40 which may be clamped down by bolts 41 to clamp bearings 42 in position so that the hub 30 can rotate as a whole about axis 34.
• the caps 40 are tensioned down by the bolts 41 to pre-load the bearings 42, so that in use, both the upper and lower load cells are always in a compressed state.
• the load cells 26 each comprise a bearing part 43 with which the bearings 42 engage, around a smaller diameter part 44 which is received by the bearing mounting parts 36, and a larger diameter part 45 received in the respective cup 38 of the channel end 37.
• a small gap provided between the bearing mounting parts 36 and the channel axle end 37 to provide a free movement of the hub 30 about the axis 34.
• the weight of the vehicle 10 on axle 23 is thus transmitted to the ground through the pair of load cells 26.
• the change in compression of the load cells 26 will be indicative of the change in load.
• the compression of the lower load cell 26 will increase, and the compression of the upper load cell 26 will decrease.
• Each load cell 26 has an inner chamber 50 and a passage 51 extending from the chamber 50 to permit electrical connections to be made with a capacitive or inductive proximity measuring device 54, mounted in chamber 50.
• the device 54 is able to measure the distance from device 54 to a chamber wall 53, with great accuracy. As the load cell 26 is subjected to a changes in compression, this distance will change by an amount depending upon the magnitude of the changing effective weight on the axle 23, as the load cell will be distorted by the load.
• the cell 26 includes a plurality of passages 52 which are arranged generally annularly around the sensor 54, which cause changes in load on the cell 26 to result in greater changes of the distance between sensor 54 and the wall 53 than otherwise would occur.
• Each proximity measuring device 54 is connected in a suitable electronic circuit arranged to operate as follows.
• the gap between the device 54 and the chamber wall 53 of the upper load cell 26 will close whilst the gap between the pin 52 and the opposite chamber wall 53 of the lower load cell 26 will open, more than a threshold amount, and the electrical circuit in which the proximity measuring devices 54 are connected may thus give a warning to the. operator that the vehicle is becoming unstable or, in addition, the electric circuit may act to prevent the operator continuing the action which is causing instability, for example by preventing further outward telescoping movement of part 20 of the boom 1.1, when the load is being moved outwardly.
• each axle 23 may carry four load cells 26, two at each end, and the electrical circuit may be arranged to average the readings from each of the four proximity measuring devices 54 to provide a very accurate continuous indication as to the actual effective weight of the vehicle transmitted through the axle 23 to the ground.
• load cell employed may be selected depending upon the general weight to which the load cell must respond, and the accuracy required. Load cells generally are known, and the detailed construction of the load cell employed does not play any particular part of the invention, provided that the load cell is adapted to be positioned as described nearer to the wheel hub 30 than the centre 25 of the axle 23.
• a load cell at each end of a rigid non oscillating axle 23 such as the front axle of the vehicle 10 carrying wheels 15, not only can the stability of the machine 10 be determined in a fore and aft direction, but by comparing different readings of the load cells 26 at each end of the axle, the lateral stability of the vehicle can be monitored, which is particularly important in a vehicle in which, for example, a load can be moved laterally of the vehicle as well as fore and aft.
• the invention may be employed not only to a loading vehicle such as shown at 10 in figure 1, but to any loading/excavating vehicle, or even to a road vehicle such as a lorry or trailer where the stability of the vehicle during loading for example needs to be monitored and/or where the actual weight of the load on the vehicle, is to be determined.
• the invention may be employed on a suspended axle arrangement provided that the load cell or cells is/are positioned adjacent to hubs carrying the ground-engaging wheels, or driven/guide wheels of a tracked vehicle, so that the load cell or cells is/are responsive to the actual weight of the vehicle transmitted to the ground through the ground engaging means.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Geology (AREA)
• Mechanical Engineering (AREA)
• Structural Engineering (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Centrifugal Separators (AREA)
• Seal Device For Vehicle (AREA)
• Vehicle Body Suspensions (AREA)
• Forklifts And Lifting Vehicles (AREA)
• Platform Screen Doors And Railroad Systems (AREA)
• Steering Controls (AREA)
• Force Measurement Appropriate To Specific Purposes (AREA)
• Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
• Glass Compositions (AREA)

Applications Claiming Priority (2)

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• 1987
  • 1987-10-15 GB GB878724206A patent/GB8724206D0/en active Pending
• 1988
  • 1988-10-14 AT AT88309655T patent/ATE74876T1/de not_active IP Right Cessation
  • 1988-10-14 CA CA000580248A patent/CA1326695C/en not_active Expired - Fee Related
  • 1988-10-14 DE DE8888309655T patent/DE3870136D1/de not_active Expired - Lifetime
  • 1988-10-14 EP EP88909348A patent/EP0341276A1/de active Pending
  • 1988-10-14 EP EP88309655A patent/EP0312390B1/de not_active Expired - Lifetime
  • 1988-10-14 WO PCT/GB1988/000864 patent/WO1989003361A1/en not_active Application Discontinuation
  • 1988-10-14 GB GB8913269A patent/GB2218528B/en not_active Expired - Lifetime
  • 1988-11-14 PT PT88763A patent/PT88763B/pt not_active IP Right Cessation

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