GB2128574A - Wind up tensioning device - Google Patents

Abstract

A wind-up and tensioning device for a belt intended to retain a load transported on a vehicle. A rotatable belt drum (8) can, by means of operation of a lever (24), be engaged with a drive motor (19) to wind up the belt (4) on the drum to its entire length or to the amount required to tension it around the load, whereby simultaneously a stop mechanism (33, 36, 37) is engaged which prevents rotation of the drum in an unwinding direction. By means of the lever (24), the drum can, further, be disengaged from the drive motor for manual unwinding of the belt, whereby the stop mechanism is simultaneously disengaged. <IMAGE>

Description

SPECIFICATION Wind-up and tensioning device for a load retaining belt The present invention relates to a wind-up and tensioning device for a belt of the type used to retain a load transported on a vehicle. Various types of tensioning devices are known and are chiefly used on lorries, particularly when transporting forest products, such as timber and pulpwood. Across the load, belts or chains are slung which are kept tensioned with a certain amount of force to prevent loosely lying logs from falling off the vehicle during transport.

The Swedish patents 326 920, 740 9199-2 and 800 3014-1 show tensioning devices of this kind. These, and other known tensioning devices for similar purposes, have certain disadvantages.

For example, hydraulic tensioning devices for chains work with a limited tensioning length, which only constitutes a small portion of the total length of the chain. After initial tensioning has been carried out in connection with loading the vehicle, the remaining tensioning length can, therefore, be insufficient to compensate for the settling of the load which occurs during transport.

The driver must, therefore, stop the vehicle after a relatively short driving distance and reset each tensioning device to its "zero" position in order to ensure a satisfactory retensioning capacity. Since this necessary safety measure is, however, timeconsuming and inconvenient, it may be neglected by the driver of the vehicle, which can entail serious risk of accidents.

In addition, when the chains are to be loosened from the load, it is time-consuming to have to gather them up in special storage boxes, as the tensioning device cannot serve as a reeling-in device for the total chain length. During journeys with the vehicle unloaded there is, further, a risk of the chains being thrown out of their storage boxes and constituting a traffic hazard.

According to, for example, the Swedish patent 800 3014-1, the chain is kept tensioned only by means of a piston-and-cylinder device actuated by a pressure medium. Since no other stop or locking device is provided, a leakage in the hydraulic system can result in a dangerous absence of tensioning force.

According to the present invention there is provided a wind-up and tensioning device for a belt, said device comprising a rotatable belt drum and, in connection with said drum, a gear reduction set for driving the drum, a pinion of said gear reduction set being axially displaceable and, by coupling means, capable of being engaged with or disengaged from an outgoing shaft of a drive motor, a control shaft, to which movement can be imparted by a manually-operable means connected thereto and adjustable between first and second dispositions, arranged thereby to effect, via movement transmitting members, an axial displacement of the pinion, and to actuate a pawl, in such a way that when the manuallyoperable means is adjusted to the first disposition, the pinion is via the coupling means engaged with the motor shaft, and the pawl simultaneously engaged with one gear of the gear reduction set to act as a back stop preventing movement of said gear in a direction opposite to the driving direction, and in such a way that when the manually operable means is adjusted to the second disposition, the pinion is disengaged from the motor shaft and the pawl is simultaneously disengaged from the gear.

An embodiment of the present invention can provide a wind-up and tensioning device for belts which presents considerable advantages in comparison with the known devices. Thus, the load retaining belt can, by means of a driving device and a belt drum, be wound-up/tensioned, its entire length or any optional portion thereof being used for wind-up and tensioning distance.

This allows, on the one hand, unlimited compensation for settling of the load during transport, on the other hand convenient winding up and storage of the belt on the drum, when it is not in use. This coupling device is made so that the engaging of the drive simultaneously results in the engaging of a back stop which secures the belt in its existing position in case of absence of driving force; whereas the disengaging of the driving device simultaneously results in the disengaging of the back stop, so that the belt can be pulled off the drum by hand unhindered by the back stop and without the drum running heavily due to its having to rotate the driving device.The pulling force supplied by the driving device can, in addition, during the last stage of the wind-up operation for storage of the belt on the drum, be utilized to tension the belt in order to squeeze water out of it to prevent the formation of ice. The back stop prevents unintentional unwinding of the belt after storage on the drum. The stop is fitted with a device which makes it work silently and which, further, greatly reduces wear. An embodiment of the present invention can be so designed that all parts pertaining to the driving, coupling and stop mechanisms are well built-in and protected, in addition to which the device requires little space.

Reference is made, by way of example, to the following drawings illustrating a device embodying the present invention, in which: Fig. 1 shows a timber-loaded vehicle fitted with a number of the devices; Fig. 2 is a side view of the device, the belt drum being shown without a belt attached to it; Fig. 3 is a partially sectional perspective view of the device: Fig. 4 is a detail view, partly sectional along the line A-A in Fig. 3, and Fig. 5 is a sectional view along the line B-B in Fig. 4.

In Figure 1, the numeral 1 denotes a vehicle with a load 2. The numeral 3 denotes the device in accordance with the invention as a whole. The device is fitted with a belt 4 and further comprises a housing 5 with holes 6 for attaching the device to the vehicle, as shown in Figs 2 and 3. Referring to Figs. 3, 4, 5, the housing is provided with a fixed shaft 7, on which a belt drum is rotatably Journalled. The drum has an outer end wall 9, which is secured to the drum by means of screws 10. A screw 11, which passes through the centre of the outer end wall and into the shaft 7 forms, together with a bearing washer 12, an axial bearing which retains the drum on the shaft.

Further, a screw 1 3 passes through the outer end wall 9, just outside the periphery of the drum, and into an inner end wall 14, for fastening a belt 4 to the drum. The inner end wall 14 is, at its periphery, formed with a flange 1 5 as shown in Fig. 4. The flange has an internal gear ring 16, which is engaged by a pinion or gear wheel 1 7 as shown in Fig. 5. The gear wheel isjournalled rotatably and is axially movable a short distance on an outgoing shaft 1 8 of a fluid motor 19 mounted on the housing 5.Referring to Fig. 4, the gear wheel 17 is, at one end, fitted with a jaw coupling half 20, which by means of axial displacement of the wheel can be moved into and out of engagement, respectively, with a corresponding coupling half 21 on the shaft 1 8, whereby the gear wheel will be made to follow the rotation of the shaft 18 and be disengaged from same, respectively. The gear wheel 1 7 is, by means of a compression spring 22, actuated in a direction of displacement causing it to be disengaged, and, by means of a coupling device 23, in a direction causing it to be engaged. The device 23 comprises a control lever 24 for turning a shaft 25. The shaft is provided with a first member protruding laterally, which can be in the form of a guide pin 26 shown in Fig. 3 passed transversely through the shaft.A balance arm 27 has a portion 28 which cooperates with the guide pin 26 along the latter's path of movement, when the shaft is turned, said portion being provided with a contact surface for the guide pin inclined relative to the plane of said path of movement.

The balance arm 27 is pivotallyjournalled on a support member 30 and is pressed against the guide pin 26 by means of a spring 29. At its end opposite to the portion 28, the balance arm is with play for its pivotal movement -- fastened to a stud 31 protruding from the gear wheel 1 7 and rotatable relative to the balance arm.

On the shaft 25 is also provided a second protruding member, which can be in the form of a guide pin 32 passed transversely through the shaft. As Figure 4 shows, a pawl 33 is provided with a recess having two side walls 34, 35 surrounding the guide pin, with play, on opposite sides of same, whereby, when the shaft 25 is rotated, a turning movement towards or away from the gear ring can be imparted to the pawl.

The pawl is journalled on the shaft 25 and is rotatable relative to same. On the pawl is fastened a bent spring member 36 which, when the pawl is swung to the position where it engages the gear ring 16, bears against said gear ring by means of a disc-shaped head 37. The head 37 is made from a non-metallic, relatively soft material which reduces both the generation of sound and wear during contact with the gear ring, when the gear reduction set is operating.

As a retainer for the position into which the coupling is adjusted, a disc 38 is provided which is fastened to the shaft 25. The disc has two holes 39 (Fig. 5) at a distance from each other, which co-operate with a spring-loaded ball of a stop device 40,41, when the control lever 26 is moved to one of its end positions a orb (Fig. 4, Fig. 5).

The housing 5 has an end wall 42 provided with a low flange 43 which encloses the end facing the housing -- of the flange 1 5 of the inner drum wall 14. Around approximately half the circumference of the end wall of the housing, and connected to the flange 43, extended side walls 44,45 are provided which cover the total width of the belt drum 8, out to its outer end wall 9.

In the side wall 44 of the housing, a sleeve 46 is pivotally fastened, through which the belt 4 is passed and which guides the winding up of the belt and functions as a stripper to keep the belt clean. At the outer end of the belt is an attachment eye 49.

When a number of devices in accordance with the invention are mounted on a vehicle, their fluid motors are connected to a fluid pump 47 having a tank for pressure fluid and a control device 48, suitably located in the cab of the vehicle (Fig. 1).

The mode of operation, with reference to a vehicle 1 fitted with a number of wind-up and tensioning devices 3 in accordance with the invention, is, in its chief outlines, as follows: When the belts 4 are to be applied for securing a load, each belt drum 8 is disconnected by means of its control lever 24, which causes both the drive from the fluid motor 19 and the pawl 33 to be disengaged (Fig. 5). The belts can now be pulled off the freely rotatable drums and thrown across the load to the opposite side of the vehicle where, by means of their eyelets 49, they are attached to fastening means - not shown - on the vehicle.

The drive coupling is then re-engaged, which operation also activates the back stop, and the belts are, by means of rotation of the belt drums of the fluid motors 19, wound up on the drums to the extent required to tension them around the load.

To carry out the wind-up operation, one can either first start the fluid pump 47 and then connect driving power from one fluid motor at a time to its respective belt drum by means of operation of each lever 24 in turn, or first set all the control levers in the driving position and then start the fluid pump, causing all the belts to be wound up simultaneously.

When the load settles during transport, the belts can be retensioned without any limitation as to the tensioning length and, consequently, without the vehicle having to be stopped for resetting of the tensioning devices. Further, the pawl 33 is all the time functioning as a back stop which secures the belt from being wound off the drum, and from losing its load retaining power in the case of a drop of pressure in the fluid system.

The mode of operation, in detail, for the engaging and disengaging of the drive of the belt drum 8 is as follows: The drive is engaged by moving the control lever 24 to position a in accordance with Fig. 5.

Hereby, the guide pin 26 of the shaft 25 turns, bearing against the inclined -- relative to the path of movement -- portion 28 of the balance arm 27 and pressing said portion outwards, causing the arm to pivot around the support 30 and, by means of its opposite end, to force the gear wheel 1 7 inwards on the outgoining shaft 1 8 of the fluid motor and the jaw coupling half 20 of the gear wheel to engage the jaw couping half 21 of the shaft. The gear wheel will now be driven, when the motor shaft is rotated, and will drive the belt drum 8 via the gear ring 1 6 of the drum's end wall 14 (Fig. 5).

Simultaneously, the guide pin 32 is turned, too, thereby engaging the side wall 34 of the recess of the pawl 33 and causing the pawl to swing to the position shown by unbroken lines in Fig. 5. When the pawl is close to this position, the turning movement of the guide pin stops, but the pawl will fall the rest of the distance due to its own weight, since it is free to move because of the clearance between the guide pin and the side walls 34, 35 of the recess (Fig. 4). Hereby, the head 37 of the spring member 36 will also come into contact with the gear ring 1 6 (Fig. 5). During a clock-wise gear movement in accordance with Fig. 5, each gear tooth will, on passing the head 37, exert a pulling force on it, causing the head - in addition to being lifted by the gear tooth - to be pulled a short distance in the clock-wise direction and thereafter, during passage of the subsequent tooth space, to swing back due to the springing action of the spring device 36. The pulling movements of the head 37 are, via the spring device 36, transmitting lifting movements to the contact end of the pawl 33, so that when passing each top of a tooth it is lifted above it and then again swung down into the subsequent tooth space.The pawl will hereby operate without metal-to-metal contact with the gear teeth, which, on the one hand, reduces the wear and, on the other hand, eliminate the strong rattling sound which would otherwise be produced by the pawl's being dragged across the teeth. The head 37 is of a nonmetallic, relatively soft material having wearreducing properties and producing little sound.

The described lifting movement of the pawl 33 is immediately replaced by a movement lowering the pawl into a stop position between two teeth, as soon as a gear movement in the counterclockwise direction is started and pulls the head 37 in this direction. The back stop is, therefore, on the one hand operating silently and without wear and, on the other hand, it ensures an immediate stopping action.

The drive is disengaged by means of moving the control leverl 24 to position b in Fig. 5. Hereby, the turning of the guide pin 26 bearing against the outer end of the inclined portion 28 of the balance arm causes the balance arm to be free to swing back due to the pressure of the spring 22 against the gear wheel 17, permitting the gear wheel to be pushed outwards on the shaft 18, so that the jaw coupling halves 20, 21 are separated from each other. Simultaneously, the guide pin 32 is turned and engages the side wall 35 of the recess of the pawl 33, causing the pawl to swing to the position shown by dash-and-dot lines in Fig. 5.

The gear ring 1 6 is now disconnected both from the pawl and the fluid motor 19, whereby the belt drum 8 can be freely rotated to pull the belt 4 off it.

At the end positions a and b of the control lever 24, the coupling positions set are secured by means of the spring 40 holding the ball 41 pressed down into a hole 39 of the disc 38, which hole corresponds to the respective position (Fig. 4, Fig. 5).

In accordance with the described embodiment of the invention a wind-up and tensioning device is obtained which is simple, reliable, requires little space, has a well built-in and protected mechanism, and which permits quick and easy handling of the load retaining belts in combination with a high degree of safety.

Through the choice of a suitable fluid motor, preferably a hydraulic motor, and a suitable reduction ratio of the gear reduction set 1 6, 1 7 are obtained, on the one hand, a suitable belt wind-up speed when no counter-force is acting on the belt, on the other hand a good pulling force at a low speed when tensioning of the belt around the load is to be carried out. In a manufactured prototype device in accordance with the invention, a pulling force of approx. 4,000 N was obtained in a working pressure of 12.5 MPa. The invention is not limited to the embodiment shown, but variations of the design are possible within the scope of the Claims.

Claims (10)

1. A wind-up and tensioning device for a belt, said device comprising a rotatable belt drum (8) and, in connection with said drum, a gear reduction set (1 6, 1 7) for driving the drum, a pinion (17) of said gear reduction set being axially displaceable and, by coupling means (20,21), capable of being engaged with or disengaged from an outgoining shaft (18) of a drive motor (19), a control shaft (25) to which movement can be imparted by a manually-operable means (24) connected thereto and adjustable between first and second dispositions (a,b), arranged thereby to effect, via movement transmitting members (27-31), an axial displacement of the pinion (17), and to actuate a pawl (33), in such a way that when the manually-operable means (24) is adjusted to the first disposition (a), the pinion (17) is, via the coupling means (20, 21) engaged with the motor shaft (18) and the pawl (33) simultaneously engaged with one gear (16) of the gear reduction set to act as a back stop preventing movement of said gear in a direction opposite to the driving direction, and in such a way that when the manually operable means is adjusted to the second disposition (b), the pinion (17) is disengaged from the motor shaft (18) and the pawl (33) is simultaneously disengaged from the gear (16).

2. A device in accordance with Claim 1, wherein the control shaft (25) is arranged to perform a turning movement and is provided with protruding members (26, 32) which, when the shaft is turned, actuate the movement transmitting members (27-31) and the pawl (33) respectively.

3. A device in accordance with Claim 2, wherein the movment transmitting members consist of a balance arm (27) pivotally journalled on a support (30) and at one of its ends bearing against one of the protruding members (26) by means of an arm portion (28) which is inclined relative to the plane of the path of movement of that protruding member, and at its opposite end being pivotally and rotatably connected to a stud (31) protruding from the pinion (17).

4. A device in accordance with claim 3, wherein the pawl (33) is provided with a recess having side walls (34, 35) which surround, with a clearance, another protruding member (32) in its two opposite directions of movement to engage the pawl with the gear (16) and disengage it, respectively.

5. A device in accordance with any of the foregoing Claims, wherein a spring (22) is arranged to actuate the pinion (17) in an axial direction causing it to be disengaged.

6. A device in accordance with any of the foregoing Claims, wherein the paw (33) is provided with a spring member (36) which, when the paw is engaged with the gear (1 6), comes into contact with said gear by means of a head (37) of a relatively soft, sound damping and wear reducing material, each gear tooth imparting, in its direction of travel, a short pulling movement to said head, said pulling movement being followed by a spring-back movement during the passage of the subsequent tooth space, whereby the spring member (36), during movment of the gear teeth in the driving direction of the belt drum (8), transmits to the pawl (33) a movement which lifts it above each gear tooth and permits it to be lowered into each tooth space without contact with the teeth, while, during movement of the gear teeth in the opposite direction, said member transmits to the pawl a lowering movement into a stopping position between two teeth, resulting in an immediate interruption of the gear movement.

7. A device in accordance with any of the foregoing Claims, wherein the coupling means (20,21) is a jaw coupling, the manually-operable means (24) is a lever, and the first and second dispositions are end positions of movement of the lever.

8. A wind-up and tensioning device for a belt, substantially as hereinbefore described with reference to Figs. 2 to 5 of the accompanying drawings.

9. A vehicle including a device, in accordance with any of the foregoing claims, for a belt intended to retain a load on the vehicle.

10. A vehicle as claimed in Claim 9, substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.