Patent Description:
A cargo tightening device for tightening lines, particularly belts or webs, comprising a ratcheting mechanism to wind the tightening lines are well known for securing a load on a means for transport on land, sea or in the air. Examples of such prior tightening devices are disclosed in the publications <CIT>, <CIT>, <CIT>, and <CIT>. <CIT> discloses a bi-directional tightening device similar to the preamble of claim <NUM>.

The prior art devices, however, suffer from the same drawback, namely that the direction of a power stroke for rotating the spool is fixed for each particular device. In this document, the power stroke refers to the direction in which the handle is moved in order to engage the drive pawl with the ratchet mechanism. The power stroke may be either a "pull" stroke or a "push" stroke. A pull stroke may be advantageous when an operator can use his or her body weight to assist in moving the handle. However, in some situations, typically when the tightening device is at a low level with respect to the operator, it may be more convenient for the operator to provide a "push" stroke for moving the handle.

Publication <CIT> discloses a pawl lever block provided with attachment element suspended and connected to a wire rope to displace a gear rack such that the gear rack is displaced by driving ratchet wheel so as to allow goods to be bundled and stably packed by proper wire rope tension. The lever block is provided with a ratchet wheel formed with an annularly arranged ratchet teeth on a rotary axis. The gear rack is arranged on a support and engaged with the ratchet teeth of the ratchet wheel. An attachment element is arranged on the gear rack such that another attachment element is fixed at a certain point. The former attachment element is suspended and connected to the wire rope to displace the gear rack such that the gear rack is displaced by driving the ratchet wheel.

Publication <CIT> discloses a bi-directional tightening device for tightening of a threadable line and an anchoring line. The device is configured for allowing an operator to select the power stroke to be a "pull" stroke or a "push" stroke simply by inverting a connection position of the threadable line and the anchoring line with respect to the tightening device. Thus, the operator must select a "pull" stroke configuration or a "push" stroke configuration prior to connecting the threadable line and anchoring line to the device.

The object is achieved through features specified in the description below and in the claims that follow.

The inventor has surprisingly found that it is possible to make a tightening device that allows an operator to select between a "push" stroke or a "pull" stroke even after the threadable line and an anchoring line have been connected to the apparatus.

In a first aspect of the invention there is provided a bi-directional tightening device for tightening of a threadable line, the tightening device comprising:.

The ratchet mechanism comprises at least one first ratchet wheel for rotating the spool in a first direction and at least one second ratchet wheel for rotating the spool in a second direction opposite the first direction, the drive pawl and the locking mechanism being sideways and radially displaceable, and provided with protrusions configured for selectively engaging either one of the ratchet wheels, to allow bi-directional tightening of the line.

By selecting which one of the first ratchet wheel and the second ratchet wheel to be engaged by the drive pawl and the locking mechanism, an operator can select whether tightening of the threadable line shall be performed by applying a "push" stroke or a "pull" stroke, even after the threadable line has been inserted through the aperture of the rotatable spool.

When in operation, an additional anchoring line is connected to a portion of the tightening device in a way known per se. End portions of both the threaded line and the anchoring line facing away from the tightening device are typically provided with attachment means, for example a hook, for engaging a portion of a substructure. In an active position wherein the tightening device ties an object to a substructure, the threaded line and the anchoring line may be subject to considerable tension and portions of at least one of the lines may abut tightly against the object.

Another effect of selecting either the first ratchet wheel or the second ratchet wheel to be engaged by the drive pawl and the locking mechanism, is that a tension in the threaded line and the anchoring line may be reduced in a controlled manner simply by repositioning the engagement of the drive pawl and the locking mechanism from one of the first ratchet wheel or the second ratchet wheel, to the other one of the second ratchet wheel and the first ratchet wheel, respectively. Contrary to prior art tightening devices, a minor slack in the lines may thus be provided without fully releasing the tension in the lines and possibly losing engagement between for example the hooks of the lines and the substructure.

In one embodiment the at least one first ratchet wheel comprises a set of two ratchet wheels, and the at least one second ratchet wheel comprises a set of two ratchet wheels. Providing two ratchet wheels of each type is advantageous with respect to transferring torque from the drive pawl to the spool via the ratchet wheels.

In one embodiment, the first ratchet wheels and the second ratchet wheels are arranged alternating along a longitudinal axis of the spool.

The drive pawl and the locking mechanism may be configured for being operated independently of each other, i.e. individual operation. Individual operation of the drive pawl and the locking mechanism makes possible arranging the drive pawl in engagement with one of the at least one first ratchet wheel for rotating the spool in a first direction and at least one second ratchet wheel for rotating the spool in a second direction opposite the first direction, while the locking mechanism may be arranged into engagement with the other one of the at least one second ratchet wheel or the at least one first ratchet wheel that are not engaged with the drive pawl. This has the effect that the spool is prevented from rotation. A secure locking of the tightening device may thus be achieved independently of a position of the part of the frame comprising the handle.

In a second aspect of the invention there is provided a method of operating of a bi-directional tightening device according to the first aspect of the invention, the method comprises the steps of:.

The method may comprise arranging the locking mechanism into engagement with the same ratchet wheel as the drive pawl to provide a tightening device operable in a push or a pull mode.

The method may comprise arranging the locking mechanism into engagement with the opposite ratchet wheel as the drive pawl to provide a locking of the tightening device.

The drive pawl and the locking mechanism may be operated independently of whether the spool carries a line. The method may thus comprise operating the drive pawl and the locking mechanism after a line has been threaded onto the spool. Thus, an operator can select which one of the first rotation direction and the second rotation direction to be activated even after the line has been inserted through the spool.

The method may comprise slackening of a threaded line in a controlled manner by releasing the drive pawl and the locking mechanism from engagement with one of the first and second ratchet wheel to the other one of the second and first ratchet wheel; and slackening of the line by means of operating the handle of the frame.

In the following is described an example of a preferred embodiment illustrated in the accompanying drawings, wherein:.

In the figures, positional indications such as for example left, right, and sideways, refer to the position shown in the figures.

Same or corresponding elements are indicated by same reference numerals. For clarity reasons some elements may in some of the figures be without reference numerals.

In the figures, reference numeral <NUM> denotes a tightening device according to the present invention. The tightening device <NUM> disclosed herein is a modification of a prior art tightening device and the skilled person will understand a basic principle of how a ratchet mechanism operates. The discussion hereinafter therefore mainly focuses on the inventive features of the tightening device.

The tightening device <NUM> comprises a rotatable spool <NUM> provided with an aperture <NUM> for receiving a line (not shown). In the embodiment shown, such a line will typically be a strap. The spool <NUM> is constituted by two semi-circular rods <NUM>' arranged in parallel and spaced apart to provide the rotatable spool <NUM>.

The spool <NUM> is supported in a frame comprising two frame parts: a base frame <NUM>; and a drive frame <NUM>. The drive frame <NUM> is formed by two parallel arms <NUM>, <NUM>' interconnected by a spacer bolt <NUM> and a handle <NUM> comprising a bolt. The base frame <NUM> and the drive frame <NUM> are interconnected by means of the spool <NUM> threaded through complementary and overlapping apertures <NUM> and <NUM>' arranged in the base frame <NUM> and each one of the arms <NUM>, <NUM>', respectively. The apertures <NUM>, <NUM>' are best seen in <FIG>.

In the embodiment shown, the spool <NUM> is locked to the frame <NUM> by means of pins <NUM> extending through apertures <NUM>' at each end portion of the semi-circular rod <NUM>'.

A ratchet mechanism <NUM>, here in the form of four ratchet wheels <NUM>, <NUM>, <NUM>, <NUM>, is rotationally fixed to the spool <NUM>. Each one of the ratchet wheels are provided with two semi-circular apertures <NUM> as best seen in <FIG> configured for mating with the semi-circular rod <NUM>' of the spool <NUM>. The ratchet wheels <NUM>, <NUM>, <NUM>, <NUM> are threaded onto the semi-circular rods <NUM>' and is therefore rotationally fixed to the spool <NUM>. The ratchet wheels <NUM>, <NUM> are prevented from moving towards each other by means of for example a clamping sleeve (not shown) inserted through mating holes <NUM> in the semi-circular rods <NUM>'.

In the embodiment shown with four ratchet wheels <NUM>, <NUM>, <NUM>, <NUM>, a first pair of ratchet wheels is formed by the wheels <NUM>, <NUM> and a second pair of ratchet wheels is formed by the wheels <NUM>, <NUM>.

The first pair of ratchet wheels <NUM>, <NUM> has teeth and dents slanting in a first direction, while the second pair of ratchet wheels <NUM>, <NUM> has teeth and dents slanting in a second direction opposite the first direction of the first pair of teeth.

A drive pawl <NUM> is slidably coupled to a slot <NUM> in each arm <NUM>, <NUM>' of the drive member <NUM>. The drive pawl <NUM> is configured for cooperating with the ratchet mechanism <NUM>.

The drive pawl <NUM> comprises two protrusions <NUM> configured for engaging either the first set of ratchet wheels <NUM>, <NUM>, or the second set of ratchet wheels <NUM>, <NUM>. An operator selects which one of the sets of ratchet wheels to be engaged by the protrusions <NUM> by sliding the drive pawl <NUM> sideways between the two arms <NUM>, <NUM>' of the drive member <NUM>.

To facilitate sideways sliding of the drive pawl <NUM> to select which one of the sets of ratchet wheels to be engaged by the protrusions <NUM>, a length of the slot <NUM> is longer than the portion of the drive pawl <NUM> extending through the slot <NUM>. Thus, the drive pawl <NUM> is configured for sliding both sideways between the two arms <NUM>, <NUM>' of the drive member <NUM>, and radially with respect to the ratchet mechanism <NUM> and thus the spool <NUM>.

The tightening device <NUM> is further provided with a locking mechanism <NUM> configured for keeping the ratchet mechanism <NUM> in place during a return stroke of the handle <NUM>. The locking mechanism <NUM> is coupled to slots <NUM> in the base frame <NUM> and is arranged sideways slidable within the slots <NUM>.

The part of the locking mechanism <NUM> facing the ratchet mechanism <NUM> is provided with locking protrusions <NUM> configured for engaging either the first pair of ratchet wheels <NUM>, <NUM>, or the second pair of ratchet wheels <NUM>, <NUM>. Juxtaposed to either side of the locking protrusions <NUM> there is provided indents <NUM>, <NUM>. The purpose of the indents <NUM>, <NUM> is to accommodate the set of ratchet wheel that are not being engaged by the protrusions <NUM> of the drive pawl <NUM>.

The part of the locking mechanism <NUM> facing away from the ratchet mechanism <NUM> is provided with a resilient member, here in the form of a spring <NUM>, to urge the locking protrusions <NUM> into engagement with either the first pair of ratchet wheels <NUM>, <NUM> or the second pair of ratchet wheels <NUM>, <NUM>, as selected by an operator. The spring <NUM> is carried by a pin <NUM> protruding from the locking mechanism <NUM>, and the spring <NUM> abuts against a retaining element <NUM> protruding from a portion of the base frame <NUM>. To allow sideways sliding of the locking mechanism <NUM>, the retaining element <NUM> is provided with a slot for accommodating an end portion of the pin <NUM>.

To allow inter alia a radial movement of the locking mechanism <NUM> when the protrusions <NUM> slide over a top of the teeth, a length of each slot <NUM> is longer than the portion of the locking mechanism <NUM> extending through the slots <NUM>. Thus, the locking mechanism <NUM> is configured for sliding both sideways within the base frame <NUM>, and radially with respect to the ratchet mechanism <NUM> and thus the spool <NUM>. In the embodiment shown, this radial movement of the locking mechanism <NUM> is also provided by an operator when releasing a tension in a line tightened by the device <NUM>.

Turning now to <FIG> showing the tightening device <NUM> in a first or "push" configuration. The drive pawl <NUM> has been slid to the right in <FIG> and <FIG> (and thus to the left in <FIG> wherein the device <NUM> is seen from behind). In this position, the protrusions <NUM> of the drive pawl <NUM> engage the first set of ratchet wheels <NUM>, <NUM>. Thus, when the drive frame <NUM> is urged in the direction of the arrow D1 shown in <FIG>, the ratchet mechanism <NUM> and thus the spool <NUM> is rotated counterclockwise with respect to the view in <FIG>. During a return stroke (in an opposite direction of the arrow D1), the drive pawl <NUM> moves radially back and forth with respect to the ratchet mechanism <NUM> as the protrusions <NUM> pass over the teeth of the ratchet wheels <NUM>, <NUM>. The drive pawl <NUM> is urged radially towards the ratchet mechanism <NUM> by means of a biasing means, here in the form of a pin member <NUM> protruding from the arm <NUM> and engages an aperture <NUM> in the drive pawl <NUM>.

As best seen in <FIG>, a periphery of the second pair of ratchet wheels <NUM>, <NUM> is "accommodated" in the indents <NUM> of the locking mechanism <NUM> so that ratchet wheels <NUM>, <NUM> are not engaged by the locking mechanism <NUM>. Thus, in this "push" configuration, the second pair of ratchet wheels <NUM>, <NUM> are neither engaged by the protrusions <NUM> of the drive pawl <NUM>, nor the locking device <NUM>. The second pair of ratchet wheels is in a passive mode.

In <FIG> is also shown a strutting member <NUM>" secured to the base frame <NUM> for example by means of a weld. A purpose of the strutting member <NUM>" is to stabilize the portion of the base frame <NUM> surrounding the apertures <NUM>. The apertures <NUM> are best seen in <FIG>.

To prevent the ratchet mechanism <NUM> and thus the spool <NUM> from rotating during a return stroke, i.e. a stroke in the opposite direction of the arrow D1 in <FIG>, the locking mechanism <NUM> has also been slid to the right in <FIG> and <FIG> (and thus to the left in <FIG> wherein the device <NUM> is seen from behind). In this position, the protrusions <NUM> of the locking mechanism <NUM> engages the first set of ratchet wheels <NUM>, <NUM> and prevents the ratchet mechanism <NUM> and thus the spool <NUM> from rotating.

In <FIG>, the tightening device <NUM> is in a second or "pull" configuration. The drive pawl <NUM> has been slid to the left. In this position, the protrusions <NUM> of the drive pawl engage the second set of ratchet wheels <NUM>, <NUM>. Thus, when the drive frame <NUM> is urged in the opposite direction of the arrow D1 shown in <FIG>, the ratchet mechanism <NUM> and thus the spool <NUM> is rotated clockwise when spool <NUM> is seen from right to left. During a return stroke (which in <FIG> will be in the same direction as the arrow D1 in <FIG>), the drive pawl <NUM> moves radially back and forth with respect to the ratchet mechanism as the protrusions <NUM> pass over the teeth of the ratchet wheels <NUM>, <NUM>.

To prevent the ratchet mechanism <NUM> and thus the spool <NUM> from rotating during a return stroke in the "pull" configuration shown in <FIG>, the locking mechanism <NUM> has also been slid to the left. In this position, the protrusions <NUM> of the locking mechanism <NUM> engage the second set of ratchet wheels <NUM>, <NUM> and prevent the ratchet mechanism <NUM> and thus the spool <NUM>, from rotating.

In the embodiment shown in <FIG> and <FIG>, the tightening device is in a locked configuration. The protrusions <NUM> of the drive pawl <NUM> engage the second set of ratchet wheels <NUM>, <NUM>, while the locking mechanism <NUM> is oriented so that the protrusions <NUM> engage the first set of ratchet wheels <NUM>, <NUM>. The ratchet mechanism <NUM> and the spool <NUM> are therefore prevented from rotating, and the drive frame <NUM> is prevented from movement with respect to the rest of the tightening device <NUM>. The configuration shown in <FIG> and <FIG> may be important when there is a need for safe locking of the tightening device.

<FIG> is a principle exploded view of the tightening device shown in <FIG>.

Claim 1:
A bi-directional tightening device (<NUM>) for tightening of a threadable line, the tightening device (<NUM>) comprising:
- a rotatable spool (<NUM>) provided with an aperture (<NUM>) for receiving the line;
- a frame (<NUM>, <NUM>) for supporting the spool, the frame comprising a handle (<NUM>) for rotating the spool (<NUM>);
- a ratchet mechanism (<NUM>) rotationally fixed to the spool (<NUM>);
- a drive pawl (<NUM>) coupled to the frame (<NUM>) and configured to engage the ratchet mechanism (<NUM>) when the handle (<NUM>) is stroked to rotate the spool (<NUM>);
- a locking mechanism (<NUM>) configured for keeping the ratchet mechanism (<NUM>) in place during a return stroke of the handle,
the ratchet mechanism (<NUM>) comprising at least one first ratchet wheel (<NUM>, <NUM>) for rotating the spool (<NUM>) in a first direction, and at least one second ratchet wheel (<NUM>, <NUM>) for rotating the spool (<NUM>) in a second direction opposite the first direction,
characterised in that the drive pawl (<NUM>) and the locking mechanism (<NUM>) is sideways and radially displaceable, and provided with protrusions (<NUM>, <NUM>) configured for selectively engaging either one of the ratchet wheels ( <NUM>, <NUM>; <NUM>, <NUM>), to allow bi-directional tightening of the line.