Background of the Invention

1. Field of the Invention The present invention relates generally to torque indicators and, more particularly, to an audio torque indicator positionable between a pair of rotatable members for gaging the torque experienced by the members and for providing both visual and audio indications of the magnitude of the torque.

2. Discussion of the Prior Art

In the installation of earth anchors, it is known to employ a hydraulic drive motor attached through a suitable installation torque head to an anchor installing tool in order to deliver a rotary driving force to the anchor installing tool. An anchor attached to an elongated rod is received within the anchor installing tool, and the anchor mates with the tool such that the anchor rotates with the tool. The anchor includes a helical load-bearing element which penetrates the earth as the anchor is rotated in order to position the anchor and rod at a desired depth beneath the surface of the ground.

There is a known relationship between the load-bearing capacity of an earth anchor and the torque with which the anchor is installed; specifically that as the torque required to install the anchor increases, the load-bearing capacity of the anchor to carry loads exerted on the rod to which the anchor is attached also increases. Thus, if the magnitude of the potential load to be carried by the anchor is known, then it is possible to install the anchor until the torque required to turn the anchor reaches a magnitude corresponding to the magnitude of the potential load. In order to monitor the torque between an installation torque head and an anchor installing tool.

and thus to gage the torque exerted on the anchor being installed by the tool, it is conventional to position a torque indicator between the torque head and tool. An example of a known type of torque indicator is a shear pin torque indicator which includes a pair of axially aligned cylindrical disks which are movable relative to one another. One of the disks is fastened to the torque head and the other to the installing tool, and one or more shear pins are placed between the two disks in order to prevent the disks from rotating relative to one another until the torque experienced by the disks is sufficient to shear the pins. After shearing of the pins, the indicator becomes "free wheeling" to prevent the anchor from being driven deeper.

By controlling the number of shear pins used in a shear pin torque indicator, it is possible to set the magnitude of torque at which installation of the anchor is considered complete. Another known type of torque indicator is a hydraulic indicator which is similar to the shear pin indicator with the exception that no shear pins are used. Instead, a hydraulic load cell is interposed between a pair of disks such that the torque experienced by the disks causes a change of pressure within the load cell which is represented by a visible gauge mounted on the indicator.

Another known type of torque indicator is illustrated in U.S. Patent No. 4,808,976, to Kiefer et al., and includes a pair of spaced cylindrical elements and a contact support connected with each of the elements. Each of the supports is provided with a contact that is spaced from the contact on the other support by a predetermined distance while the elements

are free of torsional load. When torque is applied to the elements, the contacts move relative to one another, and when a preset magnitude of torque is reached, the contacts close a circuit including an audible alarm.

None of the conventional torque indicators provide a unitary apparatus that is positionable between a drive member and a driven member and which displays the magnitude of torque being gaged by the indicator as well as providing an audible signal notifying an operator that a predetermined magnitude of torque has been achieved. Objects and Summary of the Invention

It is an object of the present invention to provide a torque indicator apparatus of unitary construction which is easily positionable between a drive member and a driven member for gaging the torque exerted on the driven member and for displaying the magnitude of the torque. It is another object of the present invention to provide a torque indicator apparatus which not only provides a visual display of torque being gaged, but also includes structure for generating at least one audible signal when a desired magnitude of torque is exceeded.

In accordance with these and other objects evident from the following description of a preferred embodiment of the invention, an apparatus for use in gaging and indicating the magnitude of torsional force exerted on a driven member by a torque drive member includes an elongated body and connection means for connecting the body between the torque drive member and the driven member so that torque exerted on the driven

member by the drive member is transmitted through the body.

The apparatus also includes electronic strain gaging means supported on the body for gaging the torsional strain experienced by the body, display means supported on the body for providing a visual display of the magnitude of the strain gaged by the gaging means, and first signalling means supported on the body for providing a first audible signal when a first preset magnitude of strain is exceeded. A power supply is supported on the body for supplying power to the gaging means, the display means and the first signalling means.

By this construction, numerous advantageous results are achieved. For example, by constructing the apparatus with a display means supported on the body or providing a visual display of the magnitude of the strain gaged by the gaging means, and first signalling means supported on the body for providing a first audible signal when a first preset magnitude of strain is exceeded, it is possible for an operator to monitor the torsional load being applied to a driven member by viewing the display provided directly on the rotating body of the apparatus. Further, even if the operator does not monitor the visual display, he or she is able to enter a preset magnitude at which the first signaling means is activated to warn the operator that the preset torque has been exceeded. Brief Description of the Drawing Figures A preferred embodiment of the inventive torque indicator apparatus is described in detail below with reference to the attached drawing figures, wherein:

Fig. 1 is a perspective view of a truck used in the installation of earth anchors, illustrating an anchor installation operation;

Fig. 2 is a perspective view of a torque indicator apparatus constructed in accordance with a preferred embodiment of the present invention, illustrating the manner in which the apparatus is supported between a drive member and a driven member;

Fig. 3 is a partially exploded plan view, taken partially in section, of the torque indicator apparatus;

Fig. 4 is a front elevational view of the torque indicator apparatus;

Fig. 5 is an exploded view of an electronics module forming a part of the torque indicator apparatus;

Fig. 6 is a front elevational view of the electronics module; and

Fig. 7 is a block diaphragm of the circuit employed in the torque indicator apparatus.

Detailed Description of the Preferred Embodiment

Turning first to Fig. 1, the equipment used for installing an earth anchor is illustrated as including a truck 10 provided with a boom having a hydraulic motor 12 supported from one end thereof. The hydraulic motor 12 is positionable and operable from a control panel on the truck, and delivers a rotary output that is transmitted through a drive member 14, which preferably includes an installation torque head, and a driven member 16, in the form of an anchor installing tool.

A torque indicator apparatus 18 constructed in accordance with a preferred embodiment of the present invention is secured between the drive member

and the driven member. As shown more clearly in Fig. 2, the torque indicator apparatus 18 is attached to the drive member 14 by an adapter 20 that is secured to the drive member and to the apparatus. A similar assembly 22 is used to secure the torque indicator apparatus to the driven member.

As shown in Fig. 3, the torque indicator apparatus 18 includes a body on which an electronics module 24, a battery pack module 26, and a pair of alarms 28, 30 are supported. The body includes a central elongated tubular member 32 having open axial ends to which annular flanges 34 are welded. Each flange extends radially outward from the tubular member 32 by a distance sufficient to house and shield the electronics module 24, battery pack module 26 and alarms 28, 30. A plurality of threaded apertures 36 are formed in the flanges to permit attachment of the apparatus to the drive and driven members 14, 16.

The tubular member 32 defines an outer surface 37 on which a four-element strain gage bridge 38 is secured. The construction of this strain gage bridge is conventional, and is arranged on the tubular member such that when the tubular member is submitted to a torsional load two arms of the four-element bridge are stretched longer while the remaining two arms are shortened. This distortion of the gage causes an increase in electrical resistance in the longer arms relative to the shorter arms, the change in resistance being proportional to the magnitude of the torque experienced by the tubular member and being measurable with the Wheatstone Bridge circuit defined by the bridge. Preferably, the strain gage bridge 38 is constructed of two bridge pairs, each provided with two resistors arranged at a 90° angle to one another.

The space defined between the flanges 34 adjacent an outer surface of the tubular member 32 is preferably filled with a potting compound material 39 or the like which permits mounting of the electronics module 24, battery pack module 26, and alarms 28, 30 on the body. This material 39 protects the modules and the alarms from the full force of the torsional strain experienced by the tubular member. Preferably, the modules 24, 26 and alarms 28, 30 are sized for friction-fit receipt within the mating cavities formed in the potting compound 39 so that some resistance to removal of the modules and alarms is provided by the material.

A pair of crescent-shaped shrouds 40 are provided for encasing the modules 24, 26 and alarms 28, 30 on the body. These shrouds are provided with windows which permit access to the modules and to the alarms while being sized somewhat smaller than the modules and alarms to provide means for retaining the modules and alarms on the body. The shrouds are fastened to the flanges 34 by screws such that they may be removed in order to permit replacement of the modules and the alarms, if necessary.

The battery pack module 26 includes a casing within which a plurality of batteries 44 are supported, and suitable wiring is connected to the batteries to provide power to the apparatus. Preferably three nine volt DC batteries are provided as the power supply for the apparatus. A modular jack assembly 46 is included in the apparatus for permitting quick manual removal and/or replacement of the battery pack module from the body without requiring the use of tools. A cover 48 is provided for the casing, and include a pair of handles by which the module may be gripped in order to expedite

removal and replacement thereof. As shown in Fig. 4, the cover 48 is secured in place on the casing by a plurality of screws 50.

As illustrated in Fig. 5, the electronics module 24 includes a casing 52 and a cover 54, wherein the cover is provided with a pair of handles by which the module may be gripped in order to expedite removal and replacement of the module. The cover 54 is retained on the casing 52 by a plurality of screws 56 positioned at the corners of the cover, as shown in Fig. 6.

Returning to Fig. 5, the electronics module includes an electronics board 58 on which the circuitry of the torque indicator is mounted. Wiring from the board to the battery pack module 26, the alarms 28, 30, and the strain gage bridge 38 extends from the board through a modular jack assembly 60 which permits quick manual removal and/or replacement of the module.

Preferably, a pair of potentiometers 62, 64 are provided on the electronics board. Each of these potentiometers is used for setting the magnitude of gaged torque required to close the circuit to the alarms 28, 30 such that each of the alarms is activated whenever the predetermined magnitude of torque, as measured by the bridge circuit 38, exceeds the setting of the potentiometer associated with that alarm.

Ideally, one of the potentiometers 62 is a low-limit control which is used by the operator to set one of the alarms 26 for activation at a first magnitude which is considered large enough to satisfy the loading requirements of the anchor being installed. The other potentiometer 64 is then used to set a second magnitude which signals the maximum allowed torsional loading of the anchor being installed.

By providing both alarms 28, 30, an operator is signalled by activation of the alarm 28 once the low-limit magnitude has been exceeded, and may continue to rotate the anchor into the earth to a desired depth or until the second alarm 30 is activated signalling the safe torsional load limit of the anchor.

As illustrated in Fig. 6, screws 66, 68 are provided for adjusting the setting of the potentiometers 62, 64, the screws extending through the cover 54 in order to be accessible while the module 24 is secured to the body. An on/off switch 70 is also provided on the front of the module as is a "zero" adjustment knob 72, a light switch 74, a low-limit read button 76, and a high-limit read button 78. A digital display 80, such as an LCD, is also provided on the module 24 and is visible through the cover 54.

The "zero" button 72 permits the display to be set at zero when the apparatus is turned on and no torque is being applied. The light button 74 activates lighting means for illuminating the display. The low- limit read button 76 is used to display the present setting of the low-limit potentiometer 62, and may be depressed during setting of the potentiometer to assist the operator in determining the magnitude at which the low-limit alarm 28 is to be activated. The high-limit read button 78 performs the same function in connection with the high-limit potentiometer 64.

A block diaphragm illustrating the circuit of the apparatus is provided in Fig. 7. The four-element strain gage bridge 38 which makes up the Wheatstone Bridge is connected to an instrumentation amplifier 82. The instrumentation amplifier, although not specifically identified in Fig. 5, is supported on the electronics board 58 within the electronics module 24.

The amplified signal from the Wheatstone Bridge is input to an analog-to-digital-converter 84, as shown in Fig. 7, and is converted into digital information which is decoded by a decoder and made available to the display 80. The digital information is preferably displayed on a liquid crystal display, although other known types of displays may be used. The amplified signal from the Wheatstone Bridge is also compared with the settings of the low-limit and high-limit potentiometers in a pair of window comparators 86, 88, and, if the signal is in excess of either of the potentiometer settings, then one or both of the audible alarms are activated. The power supply provided by the batteries is connected with the circuit to power operation thereof.

During installation of an earth anchor, an operator installs the torque indicator apparatus 18 between the drive member 14 and the driven member 16 by fastening bolts through the adapters 20, 22 provided on the members and into the threaded apertures 36. By fastening the torque indicator apparatus between the members 14, 16 in this fashion, the apparatus rotates with the members during installation of an anchor.

If necessary, the low-limit potentiometer 62 may be adjusted by rotating the setting screw 66 in order to set the magnitude of torque at which activation of the low-limit alarm 28 is desired. Preferably, the alarm is set for activation at a minimum torque determined to be sufficient to carry the load expected to be applied to the earth anchor. In this manner, even if the display is not being monitored, once the low-limit torque has been exceeded, the low-limit alarm will sound, giving the operator an audible indication that the desired torque has been

reached. By providing a low-limit alarm having a sound which differs from the sound produced by the high-limit alarm, an operator is able to discern which of the alarms has been activated. The high-limit potentiometer 64 may also be set, if necessary, in the same manner as the low-limit potentiometer by employing the high-limit setting screw 68, in order to establish the magnitude of torque sufficient to activate the high-limit alarm 30. Preferably, the high-limit alarm is activated at a magnitude of torque which represents the maximum to which the anchor is designed to be submitted, allowing for a safety factor. Thus, the setting is below the actual strength of the anchor. Once the low-limit and high-limit potentiometers are set, installation of the anchor proceeds in a conventional manner, with the visual display providing a constant output illustrating the magnitude of torque being experienced by the torque indicator apparatus. An observer standing near the torque indicator apparatus can read the display and convey this information to the operator of the hydraulic motor, or the operator can simply install the anchor until the low-limit alarm is activated. Thereafter, the operator may continue to install the anchor knowing that the low-limit threshold of installation torque has been reached.

One reason for continuing installation of the anchor beyond the low-limit threshold of torque is that, frequently, the rod connected to the earth anchor is longer than the depth of the anchor, and the anchor must be driven to a depth suitable to position the upper end of the rod close to the ground surface. Thus, even though the low-limit threshold is reached

when the anchor is only several feet beneath the earth, installation is continued until either the rod is properly positioned or the high-limit alarm is activated. Although the invention has been described with reference to the illustrated preferred embodiment, it is noted that substitutions may be made and equivalents employed herein without departing from the scope of the invention as recited in the claims.