AU2005200518B2 - Powered tarpaulin system - Google Patents

Abstract

- 15 A powered tarpaulin system for a truck/trailer comprising 5 an axle on which is wound a tarpaulin or flexible cover, the axle being positioned along the top of the truck/trailer, a demountable drive mechanism coupled to a drive shaft adapted to engage the axle, the drive mechanism comprising a motor having an output shaft 10 secured to the drive shaft and a torque arm positioned between the motor and a reaction surface on the truck/trailer, and a control means to control operation of the motor whereby the demountable drive mechanism is positioned in a readily accessible position remote from 15 the axle. H:\nicolab\keep\Speci\P55868 speci.doc 7/02/05 cm

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): RAZOR INTERNATIONAL PTY LTD A.C.N. 085 220 239 Invention Title: POWERED TARPAULIN SYSTEM The following statement is a full description of this invention, including the best method of performing it known to me/us: - 2 POWERED TARPAULIN SYSTEM This invention relates to a powered tarpaulin system for 5 use with truck and trailer bodies. The current method of covering open top articulated trailer bodies and truck bodies involving the rolling of a tarpaulin or flexible cover to cover the opening is 10 ergonomically unsound. In particular transport operations where there is a need to load bulk materials, such as grains and the like, from above the truck/trailer body there is a need for the open top of the body to be covered to eliminate the spoilage of the goods from weather and to 15 minimise the loses of goods from wind draughts while in motion. In a typical application where such a cover or tarpaulin is deployed it is rolled over the open top of the trailer body or truck body from one side to the other, typically from the curbside of the truck/trailer body to 20 the roadside. The tarpaulin is rolled onto an axle. The axle is rotated by the application of an external force such as a manual cranking force applied though the connection to the axle. In another scenario a motor can be attached to the end of the axle itself to apply the rotary 25 motive force. In these instances to ensure the tarpaulin will unroll from the axle and transverse across the top of the truck/trailer body a separate lateral force is applied to ensure the axle does not just spin on the spot to thereby also keep the tension of the tarpaulin itself. The 30 action of winding up the tarpaulin does not need assistance as the tarpaulin itself in wrapping around the axle provides the lateral force to move it across the top of the truck/trailer body. 35 The inclusion of a powered device such as a geared electric motor eliminates the ergonomic issues associated with a manual system. Previous attempts to power tarpaulin H:\nicolab\keep\Speci\P55868 speci.doc 7/02/05 - 3 systems has involved the use of a drive motor directly coupled to the axle. While this is a simple system and therefore has merit it has two major shortcomings. 5 Firstly, in the event of motor failure there is a requirement to service the motor. This is a significant issue as by the very nature of the application the drive motor is located at a height on the truck/trailer body that cannot be safely reached without an appropriate 10 elevated work platform. Therefore it is unsafe to address a motor failure in other than a workshop environment. This is impractical and indeed will generally not occur, as the expediencies of the industry cannot tolerate the lost time that this would involve. 15 Secondly, to ensure a cover is effective it needs to be taut, thus requiring a high motor torque to tension the tarpaulin across the top of the truck/trailer body. This requires a relatively large geared motor. As the geared 20 motor is mounted on the tarpaulin system axle which is already the widest point of the truck/trailer body will result in the trailer width either being outside industry limits or alternatively the trailer will have to be fabricated with less width. Both options are very 25 undesirable. The geared motor located in such an exposed location can also be prone to damage as it is the highest, widest and foremost point on the truck/trailer body. Current methods of tensioning tarpaulins on truck/trailer 30 bodies have used either long metal tension spring or long elastic fibre (rubber)cord based systems that may or may not be used in conjunction with cables, separately mounted pulleys and the like. All of these variants generate an increasing force as the tarpaulin travels across the 35 truck/trailer body. They are difficult to initially fit and are time consuming to replace or repair. In particular the elastic fibre style of tensioning system otherwise H:\nicolab\keep\Speci\P55868 speci.doc 7/02/05 known in the industry as a bunglee" has a very short useable life. The variance in the tension may also lead to shorter tarpaulin life due to inconsistency in the S tensioning of the tarpaulin as it travels over the roof of the truck/trailer. It is these issues that have brought about the present invention. 10 According to one aspect of the present invention there is provided a powered tarpaulin system for a truck/trailer comprising an axle on which is wound a tarpaulin or flexible cover, the axle being positioned along the top of 15 the truck/trailer, a demountable drive mechanism coupled to a drive shaft having an axis substantially perpendicular to the axis of the axle, the drive shaft being coupled to the axle through a right angled gearbox; the drive mechanism comprising a motor having an output 20 shaft secured to the drive shaft and a torque arm positioned between the motor and a reaction surface on the truck/trailer; and a control means to control operation of the motor whereby the demountable drive mechanism is positioned in a readily accessible position remote from 25 the axle. In a preferred embodiment the drive shaft and axle are displaceable along the top of the truck/trailer body. Preferably, the drive shaft is constrained for pivotal 30 movement to accommodate the movement of the axle. The motor is either an electric, pneumatic or hydraulic motor. 2970845_1 (GHMatters) P52131.AU-1 22/11/11 - 5 Preferably the control of the motor relies on load sensing and cut-out to ensure that the tarpaulin is consistently and evenly tensioned. 5 In a preferred embodiment a tension device is provided to tension the tarpaulin or flexible cover as it is unwound onto the top of the truck/trailer body. 10 Preferably the tensioning device is a compact self contained readily demountable mechanism. Embodiments that constitute the prior art as well as an embodiment of the invention will now be described by way 29708451 (GHMatters) P5211.A.1 22/11/12 - 6 of example only with reference to the accompanying drawings in which: Figure 1 is a perspective view of a known manually powered tarpaulin system on the roof of an 5 articulated trailer, Figure 2 is a perspective view of a known powered tarpaulin system on the roof of an articulated trailer, Figure 3a is a perspective view of a powered tarpaulin system in accordance with one embodiment of the 10 present invention in a rolled up configuration, Figure 3b is a perspective view of the assembly shown in Figure 3a in a substantially unrolled configuration, and Figure 4 is a perspective partially exploded view 15 of a tarpaulin tensioning device. Figure 1 illustrates a typical traditional manually cranked tarpaulin system. The tarpaulin axle 6 which moves laterally across the top of the truck/trailer body 4 is 20 driven via a flexible coupling 15 from a manual crank handle 16. The flexible coupling 15 in Figure 1 is typically a known universal joint. The crank handle 16 is normally stowed while in motion and is put to use to both unwind and wind up the tarpaulin cover 13. The bows 14, 25 which are attached to the truck/trailer body with standard fasteners to the industry, are used to ensure the center of the tarpaulin cover 13 and the tarpaulin axle 6 are supported against their own weight. The stops 19 are attached, typically with bolts, to the side of the 30 truck/trailer body 4 to prevent the tarpaulin cover 13 with its axle 6 from falling off the side of the body when the tarpaulin is fully rolled up. Figure 2 illustrates an improvement over the manually 35 operated system of Figure 1 with the inclusion of a drive motor 1 that is directly connected and mounted to the end of the tarpaulin axle 6. The drive motor includes an arm H:\nicolab\keep\Speci\P55868 speci.doc 7/02/05 - 7 18 that allows for the torque reaction of the drive motor 1 while still allowing the drive motor 1 to traverse with the tarpaulin axle 6 across the top of the truck/trailer body 4. 5 Figures 3a and 3b illustrate the preferred embodiment of this invention. The drive for the tarpaulin axle 6 is positioned remote 10 from the axle at a position towards the base of the forward end of the truck 4. The axle 6 is connected to a drive shaft 3 via a right angled gearbox 7. The drive shaft 3 comprises a casing 20 which houses a shaft 9 that is coupled to the axle 6 via the gearbox 7. The lower end 15 of the drive shaft 3 is located in a tapered bracket assembly 5 that is bolted to the forward end of the truck/trailer as shown in Figure 3b. The bracket assembly 5 locates the drive shaft 3 but also allows it to pivot in a vertical plane through the positions as shown in Figure 20 3a and 3b. The drive is imparted by an electric motor 1 that has an output shaft 10 in the form of a collar that can be pinned to the drive shaft 9 through a suitable pin 11. The casing 20 of the drive shafts has secured to it a bracket 2 which in turn defines a cylindrical torque arm 25 23 that is arranged to locate within an aperture 21 in the casing of the electric motor 1. In this manner the torque that is transmitted by the output shaft 10 has a reaction surface to cause rotation of the shaft without rotation of the motor 1. 30 In the unrolled position shown in Figure 3a the tarpaulin axle has been displaced to the curb side of the vehicle to rest against stops 19. Tensioning devices 12 and as detailed in Figure 4 are provided at either end at the top 35 of the trailer and these are coupled to the axle 6 via a flexible cable 8 to keep the end of the tarpaulin taut. Thus, as the drive motor 1 unrolls the tarpaulin from the 2970$45_; (GKMatters) P52131 AJ-2 22/11/11 -8 axle 6 the tensioning device 12 and the flexible cables 8 hold the tarpaulin taut and cause the axle to move across the top of the trailer from the position shown in Figure 3a to the position shown in 3b and thus prevent the 5 likelihood of the tarpaulin simply unrolling without the axle moving across the trailer. Although an electric motor is the preferred form of drive means it is understood that the motor could be pneumatic 10 or hydraulic. Furthermore, the tensioning means 12 illustrated in Figures 3a and 3b is merely schematic and it is understood that many other forms of tensioning means could be provided to ensure that the tarpaulin remains taut when it is unrolled. The rolling up of the tarpaulin 15 does not require the tensioning means because as the tarpaulin shortens it will pull the axle 6 across the top of the trailer. In another embodiment, not illustrated, the drive motor 1 20 may be mounted via another right angle gearbox located at the base of the drive shaft 3 such that the drive motor 1 and the tarpaulin axle 6 are parallel. Figure 4 illustrates a preferred embodiment of the 25 tensioning device of this invention. The tensioning device illustrated in Figure 4 essentially comprises a combination of a gas strut that is coupled to the tensioning cable 8 via a pulley system. The gas strut 30 and pulley system are located within an elongate outer housing 20 of square cross-section. The housing 20 is bolted to the front face of the truck/trailer body through bolts 29 that engage a clamp 30. The gas strut is in form of an elongate cylinder 26 that is secured centrally of a 297024si (GHMatters) P52131.AU.1 22/11/11 - 9 mounting flange 24 at one end and supports a block 22 at the other. The flange 24 and block 22 are firmly secured to the inner surface of the outer housing 20. A piston 27 is arranged to be a sliding fit within the gas cylinder 26 5 and terminates at one end (not shown) in a piston head with suitable sealing rings for sliding movement within the cylinder and at the other end in a block 22 that locates within the outer housing to be a sliding fit therein. The blocks 22 of the piston and the end of the 10 cylinder both support a pair of spaced apart pulleys that rotate on pins 28 with their axes of rotation mutually perpendicular. The tensioning cable 8 that is secured to the tarpaulin axle 6 via bolt 32 first travels around an idler aligning pulley 25 that is mounted to the trailer 15 body 31 to extend into the housing 20 and round a first pulley 33 that is mounted to the piston block 22 to return through the housing round a first pulley 34 mounted to the cylinder to return through the housing to a second pulley 35 mounted to the piston to in turn return though the 20 housing extend around a second pulley 36 mounted to the cylinder to finally return via the housing to be fixed to the piston block 22. This pulley arrangement with the pair of pulleys 33, 34, 35 and 36 at either end of both the piston and the cylinder gives a 4:1 stroke and thus 25 allows approximately 2,500mm of travel in the cable 8 with a piston having a maximum stroke of 625mm travel. This in turn reduces the overall length the piston and cylinder arrangement and makes the unit stronger and more compact. The outer casing is preferably constructed to be of square 30 cross-sections 60mm x 60mm and having a length of approximately 1,400mm. End caps not shown are preferably positioned on either of the housing to one of which has an aperture through which 35 the cable extends. The tensioning device described above is viewed as a particularly efficient means of providing the tension that is required on the cable 8 to ensure that H:\nicolab\keep\Speci\P55868 speci.doc 7/02/05 - 10 the axle moves across the top of the trailer as the tarpaulin unrolls. The device can be mounted horizontally or vertically to the face of the trailer in a variety of positions that suit the role the device has to play. 5 The advantage of using a gas piston and cylinder arrangement is that a gas strut provides a linear force independent of the length of the piston. This is in contrast with other tensioning means such as springs where 10 the force increases in dependence of deflection. Another advantage of gas struts is that they can be adjusted to provide a virtual infinite variety of tensioning forces. 15 As a further means of reducing the size of the gas strut is understood that instead of the pulley arrangement two gas struts could be positioned back to back within two housing. 20 The tensioning devices are positioned at either end of the trailer. The above description illustrates a typical arrangement 25 and is not limited as alternative methods may be employed to achieve the identical intended result. The mounting of the tarpaulin drive arm may be varied to achieve the same result. The invention is not limited to only existing truck and trailer mechanisms but can equally be employed 30 on new equipment. In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary 35 implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but H:\nicolab\keep\Speci\P55868 speci.doc 7/02/05 - 11 not to preclude the presence or addition of further features in various embodiments of the invention. H:\nicolab\keep\Speci\P55868 speci.doc 7/02/05

Claims (10)

1. A powered tarpaulin system for a truck/trailer 5 comprising an axle on which is wound a tarpaulin or flexible cover, the axle being positioned along the top of the truck/trailer, a demountable drive mechanism coupled to a drive shaft having an axis substantially perpendicular to the axis of the axle, the drive shaft 10 being coupled to the axle through a right angled gearbox; the drive mechanism comprising a motor having an output shaft secured to the drive shaft and a torque arm positioned between the motor and a reaction surface on the truck/trailer; and a control means to control operation of 15 the motor whereby the demountable drive mechanism is positioned in a readily accessible position remote from the axle.

2. The powered tarpaulin system according to claim 1 20 wherein the drive shaft and axle are displaceable along the top of the truck/trailer body.

3. The powered tarpaulin system according to claim 2 wherein the drive shaft is constrained for pivotal 25 movement to accommodate the movement of the axle.

4. The powered tarpaulin system according to any one of the preceding claims wherein the motor is either an electric, pneumatic or hydraulic motor. 30

5. The powered tarpaulin system according to any one of the preceding claims wherein the control of the motor relies on load sensing and cut-out to ensure that the tarpaulin is consistently and evenly tensioned. 35

6. The powered tarpaulin system according to any one of the preceding claims comprising a tensioning device 2970845_1 (GHatters) PS2131.AU.1 22/11/2.1 - 13 coupled to the axle to tension the tarpaulin or flexible cover as it is unwound onto the top of the truck/trailer body. 5

7. The powered tarpaulin system according to claim 6 wherein the tensioning device is a compact self-contained readily demountable mechanism.

8. The powered tarpaulin system according to either 10 claims 6 or claim 7 wherein the force required to tension the tarpaulin is provided by a gas strut.

9. The powered tarpaulin system according to claim 8 wherein a cable pulley arrangement is used as a mechanical 15 advantage on the force required to tension the tarpaulin.

10. A powered tarpaulin system substantially as described herein with reference to and as illustrated in the accompanying drawings. 20 297084S_2. (GHMatters) PS2131.AO.1 22/11111