AU2020256679A1

AU2020256679A1 - Boom sensor

Info

Publication number: AU2020256679A1
Application number: AU2020256679A
Authority: AU
Inventors: Ross Bowden; Andrew Donegan; Keiren GROGAN; Jay Nandakumar
Original assignee: Equipment Safety Systems Pty Ltd
Current assignee: Equipment Safety Systems Pty Ltd
Priority date: 2019-04-11
Filing date: 2020-04-14
Publication date: 2021-11-18
Also published as: WO2020206488A1

Abstract

A boom sensor (1, 101) for measuring the extent of extension of a boom of a lifting device, the boom sensor (1, 101) including a base (4, 104) mounted to the boom, the base (4, 104) being attached to a first part of the boom, a second part of the boom adapted to move relative to the first part of the boom as the boom extends or shortens. The boom sensor (1, 101, 201) further includes at least one wheel (6, 8, 106, 108) adapted to rotatably ride the boom, at least one biasing device (10a, 10b, 110) adapted to apply bias to the wheel 6, 8 to urge it into substantially constant contact with the boom; and at least one wheel position sensor (20, 22, 120, 122). In operation, the wheel (6, 8, 106, 108) contacts the second part of the boom, the wheel (6, 8) is movable relative to the base 4, 104 against the biasing device (10a, 10b, 110), pushing the wheel (6, 8, 106, 108) onto at least one boom contact surface of the second part and the wheel position sensor (20, 22, 120, 122) detects the angular position or the movement of the wheel (6, 8, 106, 108) to determine the extent of pay out or retraction of the boom.

Description

BOOM SENSOR

FI ELD OF I NVENTION

This invention relates to a boo m senso r. More particularly, this invention relates to a boom sensor for use on lifting equipment. Still more particularly, this invention relates to a boom sensor for use on proportional extending telescopic booms.

BACKGROUND ART

The following references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art. In particular, the following prior art discussion should not be assumed to relate to what is commonly or well known by the person skilled in the art, but to assist in the inventive process undertaken by the inventor(s) and in the understanding of the invention.

Boom sensors have been described in which a metered length of wire cable is paid out from and rewound onto a spool to measure the distance that a boom extends. The wire can present an extended snag hazard and can be damaged anywhere along its length making it vulnerable in environments where robust equipment is needed.

An object of the present invention is to ameliorate one or more of the aforementioned disadvantages of the prior art or to at least provide a useful alternative thereto.

STATEMENT OF I NVENTION

The invention according to one or more aspects is as defined in the independent claims. Some optional and/or preferred features of the invention are defined in the dependent claims.

Accordingly, in one aspect of the invention there is provided:

A boom sensor for measuring the extent of extension of a boom of a lifting device, the boom sensor including a base mounted to the boom, the base being attached to a first part of the boom, a second part of the boom adapted to move relative to the first part of the boom as the boom extends or shortens, wherein the boom sensor further includes:

at least one wheel adapted to rotatably ride the boom;

at least one biasing device adapted to apply bias to the wheel to urge it into substantially constant contact with the boom; and

at least one wheel position sensor,

and wherein: the wheels contact the second part of the boom;

the wheel is movable relative to the base against the biasing device, the biasing device pushing the wheel onto at least one boom contact surface of the second part; and

the wheel position sensor detects the angular position or the movement of the wheel to determine the extent of pay out or retraction of the boom.

ALTERNATIVES, OPTIONS AND PREFERM ENTS

BOOM

The first part of the boom may be curved or may be substantially l inear and have a first longitudinal axis. The second part of the boom is adapted to move relative to the first part of the boom as the boom extends or shortens. The second part of the boom is preferably adapted to extend and retract along the same contour or coaxially relative to the first part. The second part is preferably adapted to move along a second longitudinal axis which is parallel to the first longitudinal axis. In any case, the boom sensor may adapted for use on a variety of booms for l ifting devices such as small cranes, articulated lifting devices and telehandlers. The boom sensor may be adapted for installation on a custom built l ifting device during manufacture, or may be retrofitted to an existing lifting device.

BASE

The base may include a container. The container may be in the form of a housing or cover to weather-proof the base. The container may be made of materials including a composite of plastic or metal, preferably materials including metal, such as steel coated with a protective paint.

The base may include electronics such as a data processing module.

The base may include at least one angle sensor to measure the angle of the boom or its second part. Preferably, the base includes one angle sensor to measure the angle of the boom. Most preferably, the base includes one dual channel angle sensor to measure the angle of the boom. The base may include at least one accelerometer to measure movement of the boom.

The base may include at least one wireless data transmitter or receiver. Alternatively, the base does not include a wireless data transmitter or receiver, but communication is hardwired to a display at an operator console. Simi larly, the base may be powered by wire connection to a vehicle battery source, or may have an independent power source, such as a battery source housed in the base. Preferably, the electronic devices in the boom sensor uses a CAN (Controller area network) bus system to communicate. The container may partially or ful ly cover or protect the wheel position sensor, protecting it against weather, moisture, impact damage, etc. Alternatively, the container does not cover the wheel position sensor. The base may include mounting surfaces or attachment devices to mount the base to the first part of the boom.

Preferably, the base includes mounting surfaces to mount to the first part of the boom, which may enable the base to be welded, or otherwise adhered or bolted to the first part.

WH EEL

The wheel may be a first one of a plurality of wheels. Preferably, there are two wheels, including a first and a second wheel to cater for redundancy and reliabi l ity in the boom sensor. The wheel may be journaled for relatively frictionless rotation on bearings. Preferably, the wheel includes bal l bearings. The wheel may be mounted to a shaft. The first and second wheels may be mounted to a pair of shafts for rotation thereon.

The wheel may include a high friction surface (high friction rolling surface) which is adapted to come into contact with corresponding at least one boom contact surface. The wheel may be geared. The wheel may be geared on its circumference. The gears on the wheel may run along linear gear rails on the boom contact. Preferably, the wheel includes a high friction rolling surface which is adapted to come into contact with the boom contact surface.

The wheel high friction surface may include rubber or other high friction tracks around the circumference of the wheel. Preferably, the high friction surface includes at least one rubber track or tyre around the circumference of the wheel. The wheel may include at least one augmentary device as part of the wheel position sensor. The augmentary device may include a reflector or magnet that may be attached to the wheel.

BIASI NG DEVICE

The biasing device preferably connects the wheel to the base and is adapted to apply force onto the one or more wheels. The biasing device may operate by application of a magnetic force or electromagnetic force. Preferably, the biasing device is a spring device.

The biasing or spring device may be adapted and configured to work with different types of booms currently used in the industry. The invention envisages that the biased wheel may take a number of different forms and still fal l within the scope of the invention.

The spring device may be attached to the wheel. Where the boom sensor includes a plurality of wheels, there may be one spring device for each wheel. The biasing device may include one spring device for the or each wheel. Where the at least one wheel includes a pair of wheels, one biasing device may be shared between the wheels. The single biasing device may be provided for and attached to both wheels. The biasing device may be fixed to the base. The biasing device may include a pivoting attachment. The pivoting attachment may be connected to the base. The biasing device may include a pivoting attachment connected to a wheel shaft. The biasing device may be fixed to the wheel shaft.

DEFLECTABLE ARM

The biasing device may include a canti levered arm acting as a bias or spring. The cantilevered arm may be attached between, and operatively connected to, the base and the wheel. The canti levered arm may be made of metal or plastic.

The biasing device may include spiral shaped springs. The biasing device may include a spiral shaped spring connected between the base and a spring shaft on which the wheel is rotatably mounted. An arm may be fixed to and extend from the shaft to the base. The biasing device may include one or more helical springs connected between the base and the one or more wheels. The biasing device may include at least one spring that acts on an outer radial point of one or more spring shafts. The spring shaft may rotate in a hub in the base and the at least one arm may extend from the spring shaft to the at least one wheel. The biasing device may include springs acting on sleeves or other components fixed to the spring shaft.

SENSOR

There at least one wheel position sensor may include two wheel position sensors. The wheel position sensor may be positioned on the base. The wheel position sensor may be positioned on the one or more spring devices. The wheel position sensors may be positioned on wheel hubs or shafts. The wheel position sensors may be positioned on the wheels. Part of the wheel position sensor may be attached to the spring device and another part to the wheel. Preferably, the wheel position sensor is positioned on the wheel shaft. The wheel position sensor may detect movement of the wheel relative to the spring device or detect the angular position of the wheel. Preferably, the wheel position sensor detects movement of the wheel. The wheel position sensor may use photo detectors or photo transmitters. The wheel position sensor may use magnets and coils to detect position or movement of the wheels to detect movement of the wheels. The wheel position sensor may include at least one contactless magnetic sensor.

Preferably, the wheel position sensor includes one contactless magnetic sensor. The wheel position sensor may use wireless data transmitters or receivers. The boom may be a telescopic handler boom, or other crane boom. Preferably, the boom is a telescopic handler boom.

BRI EF DESCRI PTION OF THE DRAWI NGS

The invention may be better understood from the following non-l imiting description of preferred embodiments, in which:

Figure 1 is a perspective view of a a boom sensor according to a first embodiment of the invention;

Figure 2 is a perspective view of a boom sensor according to a second embodiment of the invention; and

Figure 3 is a section view through a vertical plane of the boom sensor shown in

Fig. 1 through the axis of first and second shafts 12a-b;

Figure 4 is a section view through a vertical plane of the boom sensor shown in Fig. 1 through the axis of shafts 46a-b;

Figure 5 is a plan section view of the boom sensor shown in Fig. 1 through the axis of first and second shafts 12a-b;

Figure 6 is a section view through a vertical plane of the boom sensor shown in Fig. 2 through the axis of shaft 112;

Figure 7 is a plan section view of the boom sensor shown in Fig. 2 through the axis of shafts 146a-b;

Figure 8 is a plan section view of the boom sensor shown in Fig. 2 through the axis of shaft 112;

DETAI LED DESCRI PTION OF THE DRAWI NGS

Preferred features of the present invention will now be described with particular reference to the accompanying drawings. However, it is to be understood that the features illustrated in and described with reference to the drawings are not to be construed as limiting on the scope of the invention.

In the drawings, a boom sensor 1, 101 for measuring the extent of extension of a boom of a lifting device, the boom sensor 1, 101 including a base 4, 104 mounted to the boom, the base 4, 104 being attached to a first part of the boom, a second part of the boom adapted to move relative to the first part of the boom as the boom extends or shortens. The boom sensor 1, 101 further includes at least one wheel 6, 8, 106, 108 adapted to rotatably ride the boom, at least one biasing device 10a, 10b, 110 adapted to apply bias to the wheel 6, 8 to urge it into substantial ly constant contact with the boom; and at least one wheel position sensor 20, 22, 120, 122,

In operation, the wheel 6, 8, 106, 108 contacts the second part of the boom, the wheel 6, 8 is movable relative to the base 4, 104 against the biasing device 10a, 10b, 110, pushing the wheel 6, 8, 106, 108 onto at least one boom contact surface of the second part and the wheel position sensor 20, 22, 120, 122 detects the angular position or the movement of the wheel 6, 8, 106, 108 to determine the extent of pay out or retraction of the boom.

First and second embodiments of the boom sensor 1, 101 are shown in the drawings. The first embodiment of the boom sensor 1 is designed to be mounted and operate correctly with existing booms in the industry. The second embodiment of the boom sensor 101 is designed to be mounted to and operate correctly with a custom designed boom. The third embodiment shown in Fig. 3 is also adapted for use with a custom- designed boom.

Referring to the first embodiment of the boom sensor 1, the boom sensor 1 includes a base 4, two wheels 6, 8, two spring devices 10a, 10b and two wheel position sensors 20, 22. Both wheel position sensors 20, 22 are contactless magnetic sensors. The base 4 includes a data processing module 26, a dual channel angle sensor and a housing 7. The housing 7 encloses the other the components in the base 4. The dual channel angle sensor measures the angle of the boom from the horizontal (or relative to the lifting device). The data processing module 26 converts the output signal from the two wheel position sensors 20, 22 and the dual channel angle sensor into readable signals. The readable signals are then sent to the main display which can be viewed by the operator of the lifting device. The separate devices communicate using a CAN

(Controller area network) bus system. The data sent to and from the base and the main display is sent through wires, not wireless devices.

Two spring devices 10a, 10b connect the base 4 to the two wheels 6, 8. The spring devices 10a, 10b are located on opposite sides of the first version base 4. The first spring device 10a includes a first shaft 12a, a first arm 14a, a first hub 11a, a first spring support 13a, a first spring 15a and a first shaft seal 16a. The second spring device 10b includes a second shaft 12b, a second arm 14b, a second and third hub lib, 11c, a second spring support 13b, a second spring 15b and a second shaft seal 16b.

The first shaft 12a, the first spring support 13a, the second hub lib, the second spring support 13b and the second shaft 12b al l rotate about the same first longitudinal axis Al. The first shaft 12a rotates in the first hub 11a and is fixed to the first spring support 13a. The first spring support 13a is fixed to the second hub lib. The second shaft 12b rotates in the second hub lib and the third hub 11c. This arrangement keeps the first shaft 12a and the second shaft 12b coaxial. The first shaft 12a is kept in the same axial position because the first spring support 13a contacts the first hub 11a. The first hub 11a is fixed to the housing 7. The first spring 15a is a cylindrical hel ix spring. A first end 17a of the first spring 15a is fixed to the first spring support 13a and a second end 17b of the first spring 15a is fixed to the bottom part 9b of the housing 7. Furthermore, the first spring 15a is wound clockwise from the first end 17a to the second end 17b of the first spring 15a when looking at the first spring 15a from the first end 17a. Therefore, as the first shaft 12a rotates in direction 1 D1 the first spring 15a is put in compression and appl ies a force to the first shaft 12a in direction 2 D2. The first arm 14a is positioned at a specified angle on the first shaft 12a. The first shaft 12a is then rotated in direction D1 before instal ling onto the boom. This puts the first spring 15a in a compressed state and the first spring 15a therefore applies a specified moment to the first arm 14a and a specified force pushing the first wheel 6 onto the second part of the boom. The specified force is dependent on the specified angle, therefore the specified force can be set by changing the specified angle.

The first wheel 6 is mounted to the shaft 45a of a first ball bearing 9a. The hub 44a of the first ball bearing 9a is fixed to the first arm 14a. The first wheel 6 includes a first wheel body 32a and a first wheel tread 31a. The first wheel tread 31a is made of rubber and is smooth to increase contact surface area on the second part of the boom. The first wheel body 32a includes holes to decrease weight while maintaining structural integrity. A first cover 33a is attached to the first arm 14a and encloses the side and half of the circumference of the first wheel 6. The first cover 33a is made of painted galvanized steel. The first cover 33a helps keep unwanted substances such as dust off the first wheel tread 31a and out of the first ball bearing 9a.

The first wheel position sensor 20 is secured to the first arm 14a and includes a shaft 46a which is fixed to the shaft 45a of the first ball bearing 9a. Since the wheel contacts the second part of the boom and the base 4 is fixed to the first part of the boom, as the second part moves relative to the first part, the first and second wheels 6, 8 rotate.

This also rotates the shaft of the first wheel position sensor 20. Any movement of the shaft of the first wheel position sensor 20 is detected and measured by the wheel position sensor 20. Therefore, any movement of the second part of the boom relative to the first part of the boom is measured by the wheel position sensor 20. The information from the wheel position sensor 20 is sent through the first cable 24a to a data processing module 26 inside the base 4. The data processing module 26 then converts the input data into a form readable by the display and sends the data to the display through a CAN bus wired system. The display is located next to the operator on the l ifting device. The first arm 14a is also fixed to a first end 18a the first shaft 12a with two bolts 19a, 19b. The first end 18a of the first shaft 12a is threaded and the two bolts 19a, 19b are screwed onto the first end 18a either side of the first arm 14a. The first arm 14a is also threaded and screws onto the first end 18a of the first arm 14a. This fixes the first arm 14a to the first shaft 12a. The first arm 14a is made of painted galvanized steel.

The second spring device 10b, second wheel 8 and second wheel position sensor 22 are mirrors of the first spring device 10a, first wheel 8 and first wheel position sensor 20. The second spring device 10b, second wheel 8 and second wheel position sensor 22 act as a backup and ensure the readings are accurate by comparing results from the first and second wheel position sensors 20, 22.

The first shaft 12a and second shaft 12b rotate independently of each other. The second shaft 12b is kept in the same axial position because the second spring support 13b contacts the third hub 11c. The third hub 11c is fixed to the housing 7. The second spring 15b is a cylindrical helix spring. A first end 17c of the second spring 15b is fixed to the second spring support 13b and a second end 17d of the second spring 15b is fixed to the bottom part 9b of the housing 7. Furthermore, the second spring 15b is wound anticlockwise from the first end 17c to the second end 17d of the second spring 15b when looking at the second spring 15b from the first end 17c. Therefore, as the second shaft 12b rotates in direction 1 Dl, the second spring 15b is put in

compression and applies a force to the second shaft 12b in direction 2 D2. The second arm 14b is positioned at a specified angle on the second shaft 12b. The second shaft 12b is then rotated in direction 1 Dl before installing onto the boom. This puts the second spring 15b in a compressed state and the second spring 15b therefore applies a specified moment to the second arm 14b and a specified force pushing the first wheel 6 onto the second part of the boom. The specified force is dependent on the specified angle, therefore the specified force can be set by changing the specified angle.

The second wheel 8 is mounted to the shaft 45b of a second ball bearing 9b. The hub 44b of the second ball bearing 9b is fixed to the second arm 14b. The second wheel 8 includes a second wheel body 32b and a second wheel tread 31b. The second wheel tread 31b is made of rubber and is smooth to increase contact surface area on the second part of the boom. The second wheel body 32b includes holes to decrease weight while maintaining structural integrity. A second cover 33b is attached to the second arm 14b and covers the side and half of the circumference of the second wheel 8. The second cover 33b is made of painted galvanised steel. The second cover 33b helps keep unwanted substances such as dust off the second wheel tread and out of the second ball bearing 9b.

The second wheel position sensor 22 is secured to the second arm 14b and includes a shaft 46b which is fixed to the shaft 45b of the second ball bearing 9b. Since the wheel contacts the second part of the boom and the base 4 is fixed to the first part of the boom, as the second part moves relative to the first part, the second wheel 8 rotates. This also rotates the shaft 46b of the second wheel position sensor 22. Any movement of the shaft 46b of the second wheel position sensor 22 is detected and measured by the wheel position sensor 22. Therefore, any movement of the second part of the boom relative to the first part of the boom is measured by the wheel position sensor 22. The information from the wheel position sensor 22 is sent through the second cable 24b to a data processing module 26 inside the base 4. The data processing module 26 then converts the input data into a form readable by the display and sends the data to the display through a CAN bus wired system. The data from the second wheel position sensor 22 is also compared with the data from the first wheel position sensor 20 to ensure both wheel position sensors 20, 22 are operating correctly.

The second arm 14b is fixed to a first end 18b of the second shaft 12b with two bolts 19c, 19d. The first end 18b is threaded and the two bolts 19c, 19d are screwed onto the first end 18b either side of the second arm 14b. The second arm 14b is also threaded and screws onto the first end 18b. This fixes the second arm 14b to the second shaft 12b. The second arm 14b is made of painted galvanised steel.

The housing 7 is made of two parts, a top part 9a and a bottom part 9b. The top and bottom parts 9a, 9b are fixed together with bolts 41 which forms a seal to keep unwanted substances such as dirt and water out of the housing 7. The boom sensor is powered with a power cable 42 which is supplied with power by a generator connected to the lifting devices engine. The housing 7 is made of painted galvanised steel. The housing 7 is welded to the first part of the boom for installation.

The following refers to the second embodiment of the boom sensor 101. The second embodiment of the boom sensor 101 has the same base 104 as the first embodiment of the boom sensor 1. The second embodiment of the boom sensor 101 includes the base 104, two wheels 106, 108, a spring device 110 and two wheel position sensors 120, 122. The two wheel position sensors 120, 122 are contactless magnetic sensors. The base includes a data processing module 126, an dual channel angle sensor and a housing 107.

The housing 107 encloses the other components in the base 104. The dual channel angle sensor measures the angle of the boom from the horizontal (or relative to the lifting device). The data processing module 126 converts the output signal from the two wheel position sensors 120, 122 and the dual channel angle sensor into readable signals. The readable signals are then sent to the main display which can be viewed by the operator of the l ifting device. The data sent to and from the data processing module 126 and the main display is sent through wires using a CAN bus system.

A spring device 110 connects the base 104 to the two wheels 106, 108. The spring device 110 includes a shaft 112, a first arm 114a, a second arm 114b, a first hub 111a, a second hub 111b, a spring support 113, a spring 115, a first shaft seal 116a and a second shaft seal 116b. The shaft 112 and the spring support 113 rotate about the same longitudinal axis A2. The shaft 112 rotates in the first hub 111a and the second hub 111b. The first and second hubs 111a, 111b are fixed to the housing 107. The spring support 113 is fixed to the shaft 112.

The shaft 112 is kept in the same axial position because the spring support 113 contacts the second hub 111b and the spring 115 is fixed to both the spring support 113 and the housing 107. The spring 115 is a cylindrical hel ix spring. A first end 117a of the spring 115 is fixed to the spring support 113 and a second end 117b of the spring 115 is fixed to the bottom part 109b of the housing 107. Furthermore, the spring 115 is wound clockwise from the first end 117a to the second end 117b when looking at the spring 115 from the first end 117a. Therefore, as the shaft 112 rotates in direction 3 D3, the spring 115 is put in tension and applies a force to the shaft 112 in direction 4 D4. The first arm 114a is positioned at a specified angle on the shaft 112. The shaft is then rotated in direction 3 D3 before installing onto the boom. This puts the spring 115 in a state of tension and the spring 115 therefore appl ies a specified moment onto the first arm 114a. This moment results in a specified force on the second arm 114b towards the surface of the second part of the boom and therefore appl ies a specified force on the two wheels 106, 108 towards the surface of the second part of the boom. The specified force is dependent on the specified angle, therefore the specified force can be set by changing the specified angle.

The first arm 114a is fixed to the first end 118a of the shaft 112 with two bolts 119a 119b. The first end 118a of the shaft 112 is threaded and the two bolts 119a, 119b are screwed onto the first end 118a either side of the first arm 114a. The first arm 114a is also threaded and screws onto the first end 118a. This fixes the first arm 114a to the first shaft 112. The first arm 114a is connected to a point part way along the length of the second arm 114b through a pivoting connection. This allows both wheels 106, 108 to move away from and towards the surface of the second part of the boom. This allows the spring device 110 to apply force on the wheels 106, 108 towards the surface of the second part of the boom. The first arm 114a and second arm 114b are made of painted galvanised steel.

The first wheel 106 is mounted to the shaft 145a of a first ball bearing 109a. The hub 144a of the first ball bearing 109a is fixed to a first end 143a of the second arm 114b. The first wheel 106 includes a first wheel body 132a and a first wheel tread 131a. The first wheel body 132a has holes to decrease weight while maintaining structural integrity. The first wheel tread 131a is made of rubber and is smooth to increase contact surface area on the second part of the boom.

The second wheel 108 is mounted to the shaft 145b of a second bal l bearing 109b. The hub 144b of the second bal l bearing 109b is fixed to a second end 143b of the second arm 114b. The second wheel 108 includes a second wheel body 132b and a second wheel tread 131b. The second wheel body 132b has holes to decrease weight while maintaining structural integrity. The second wheel tread 131b is made of rubber and is smooth to increase contact surface area on the second part of the boom.

The first wheel position sensor 120 is secured to the second arm 114b and includes a shaft 146a which is fixed to the 145a shaft of the first ball bearing 109a. The second wheel position sensor 122 is secured to the second arm 114b and includes a shaft 146b which is fixed to the shaft 145b of the second bal l bearing 109b. Since the first and second wheels contact the second part of the boom and the base is fixed to the first part of the boom, as the second part moves relative to the first part, the first and second wheels 106, 108 rotate. This also rotates the shafts 146a, 146b of the first and second wheel position sensors 120, 122. Any movement of the shafts 146a, 146b of the first and second wheel position sensors 120, 122 is detected and measured by the wheel position sensors 120, 122. Therefore, any movement of the second part of the boom relative to the first part of the boom is measured by the wheel position sensors 120, 122. Any information from the first wheel position sensor 120 is sent through a first cable 124a to a data processing module 126 inside the base 104. Any information from the second wheel position sensor 122 is sent through a second cable 124b to the data processing module 126. The data processing module 126 then converts the input data into a form readable by the display and sends the data to the display through a wired CAN bus system.

The housing 107 is made of two parts, a top part 109a and a bottom part 109b. The top and bottom parts 109a, 109b are fixed together with bolts 141 which forms a seal to keep unwanted substances such as dirt and water out of the housing 107. The boom sensor 101 is powered with a power cable 142 which is supplied with power by the lifting devices engine.

DEFI N ITIONS

Throughout the specification and claims the word“comprise” and its derivatives are intended to have an inclusive rather than exclusive meaning unless the contrary is expressly stated or the context requires otherwise. That is, the word“comprise” and its derivatives will be taken to indicate the inclusion of not only the listed components, steps or features that it directly references, but also other components, steps or features not specifically listed, unless the contrary is expressly stated or the context requires otherwise.

In the present specification, object terms such as“apparatus”,“means”,“device” and “member”, or similar terms, may refer to singular or plural items and are terms intended to refer to a set of properties, functions or characteristics performed by one or more items or components having one or more parts. It is envisaged that where the object term is described as being a unitary object, then a functionally equivalent object having multiple components is considered to fall within the scope of the object term, and simi larly, where the object term is described as having multiple components, a functionally equivalent but unitary object is also considered to fall within the scope of the object term, unless the contrary is expressly stated or the context requires otherwise.

Where the word“for” is used to qualify a use or application of an object term, the word“for” is only limiting in the sense that the device or component should be “suitable for” that use or application.

Orientational terms used in the specification and claims such as vertical, horizontal, top, bottom, upper and lower are to be interpreted as relational and are based on the premise that the component, item, article, apparatus, device or instrument will usually be considered in a particular orientation, typically with the top of the housing 7,107.

Claims

The claims:

1. A boom sensor for measuring the extent of extension of a boom of a lifting

device, the boom sensor including a base mounted to the boom, the base being attached to a first part of the boom, a second part of the boom adapted to move relative to the first part of the boom as the boom extends or shortens, wherein the boom sensor further includes:

at least one wheel adapted to rotatably ride the boom;

at least one wheel position sensor,

and wherein:

the wheels contact the second part of the boom;

2. The boom sensor as defined in Claim 1, wherein the base includes an inclination meter include to measure the angle of the boom or the second part thereof.

3. The boom sensor as defined in Claim 1, wherein the base includes at least one accelerometer to measure movement of the boom.

4. The boom sensor according to any one of Claims 1- 3, wherein the wheel is one of a plurality of wheels.

5. The boom sensor according to Claim 4, wherein the wheel is a first wheel and the boom sensor further includes a second wheel.

6. The boom sensor according to any one of Claims 1- 5, wherein the wheel is journalled for relatively frictionless rotation on bearings and is mounted to a shaft.

7. The boom sensor according to any one of Claims 1- 6, wherein the wheel is geared.

8. The boom sensor according to any one of Claims 1- 7, wherein the wheel has a high friction rolling surface around the circumference of the wheel.

9. The boom sensor according to any one of Claims 1- 8, wherein the biasing device connects the wheel to the base and is adapted to apply force onto the wheel.

10. The boom sensor according to any one of Claims 1- 9, wherein the biasing

device is in the form of a spring device.

11. The boom sensor according to Claim 9, wherein the biasing device is attached to the wheel.

12. The boom sensor according to any one of Claims 5 - 11, wherein the at least one wheel includes a pair of wheels and one biasing device is shared between the pair of wheels.

13. The boom sensor according to any one of Claims 1 - 12, wherein the biasing device is fixed to the base.

14. The boom sensor according to any one of Claims 1- 13, wherein the biasing device includes a pivoting attachment.

15. The boom sensor according to Claim 14, wherein the pivoting attachment is connected to the base and to a wheel shaft. The biasing device may be fixed to the wheel shaft.

16. The boom sensor according to any one of Claims 1- 15, wherein the biasing device includes a cantilevered arm acting as a bias or spring.

17. The boom sensor according to Claim 16, wherein the cantilevered arm is

attached between, and operatively connected to, the base and the wheel.

18. The boom sensor according to any one of Claims 1- 17, wherein the biasing device includes a spring shaft and at least one arm, the spring shaft rotatable in a hub in the base and the at least one arm extending from the spring shaft to the wheel.

19. The boom sensor according to any one of Claims 1- 18, wherein the wheel

position sensor is positioned on the wheel shaft and uses contactless magnet sensors to detect position or movement of the wheel.

20. The boom sensor according to any one of Claims 1- 19, wherein the boom may be a telescopic handler boom.