# US 2009/0260491 A1 · Multi-pinion gear digital beam torque wrench

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- Number: US 2009/0260491 A1
- Document ID: US20090260491A1
- Status: Published application
- Kind: A1
- Application number: 12/425,568
- Filed: 2009-04-17
- Published: 2009-10-22
- Earliest claimed: 2008-04-18
- Assignees: Brown Line Metal Works, LLC
- Inventors: Michael D. Rainone; Daniel Baxter; Thao D. Hovanky
- Web page: https://patentgrep.com/patent/US20090260491A1

## CPC

- B25B 23/1427: {by mechanical means}
- B25B 23/1425: {by electrical means}
- B25B: TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING, OR HOLDING

## Abstract

A digital torque wrench includes a position sensor assembly which measures the movement of a load beam with respect to an indicator beam to determine the torque being applied to a working element by the torque wrench. The position sensor assembly includes a first position sensor portion having multiple rotatable pinion gears coupled to a potentiometer, and includes a second position sensor portion having a rack gear that engages one of the pinion gears of the first position sensor portion. The first and second position sensor portions are attached to different ones of the load beam and the indicator beam so that at least one of the pinion gears rotates along the rack gear in response to force (torque) being applied through the load beam to the working element. Rotation of the pinion gears causes rotation of a potentiometer element, which produces a signal indicative of the relative displacement of the load beam with respect to the indicator beam. This displacement is then converted to a torque measurement and is displayed to a user via a display. The use of multiple pinion gears enables a high degree of resolution with respect to the torque measurements, while reducing the width profile of the torque wrench.

## Claims

### Claim 1

A torque wrench, comprising:
a main beam having a distal end and a proximal end;
a drive element disposed near the distal end of the main beam;
an indicator beam having a first end fixedly secured to the main beam at a first location on the main beam, and a second end;
a position sensor assembly at least partially disposed at a second location on the main beam to detect an amount of displacement of the main beam relative to the indicator beam, the position sensor assembly including:
a rack gear secured to one of the main beam or the indicator beam;
a first pinion gear in geared connection with the rack gear and secured to the other one of the main beam or the indicator beam;
a second pinion gear operatively engaged with the first pinion gear; and
a position sensor engaged with the second pinion gear to sense an amount of displacement of the main beam relative to the indicator beam.

### Claim 2 (depends on 1)

The torque wrench of claim 1, wherein the second pinion gear has a smaller diameter than the first pinion gear.

### Claim 3 (depends on 1)

The torque wrench of claim 1, wherein the position sensor includes a rotating potentiometer that generates an electrical signal indicative of the amount of displacement of the main beam relative to the indicator beam based on a rotation of the second pinion gear.

### Claim 4 (depends on 1)

The torque wrench of claim 1, further comprising:
a handle assembly disposed at the proximal end of the main beam; and
a dowel pin coupled to the main beam and to the handle assembly.

### Claim 5 (depends on 1)

The torque wrench of claim 1, wherein the rack gear is a straight gear having teeth engaged with teeth of the first pinion gear.

### Claim 6 (depends on 5)

The torque wrench of claim 5, wherein the indicator beam engages the second pinion gear via a spring.

### Claim 7 (depends on 1)

The torque wrench of claim 1, wherein the rack gear is an arcuate gear having teeth engaged with teeth of the first pinion gear.

### Claim 8 (depends on 1)

The torque wrench of claim 1, wherein the indicator beam has a flat elongated shape.

### Claim 9 (depends on 1)

The torque wrench of claim 1, wherein the rack gear is rigidly secured to the main beam and the first pinion gear is rotatably secured to the indicator beam.

### Claim 10 (depends on 1)

The torque wrench of claim 1, wherein the position sensor generates an electrical signal indicative of the amount of displacement of the main beam relative to the indicator beam; the torque wrench further comprising a circuit to generate a torque measurement based on the electrical signal.

### Claim 11 (depends on 10)

The torque wrench of claim 10, further comprising at least one of a display component or an audio component to generate at least one of a visual or an audio indication of the torque measurement.

### Claim 12 (depends on 1)

The torque wrench of claim 1, further comprising:
a gear cover having an input portion to receive the second end of the indicator beam, wherein each of the first pinion gear and the second gear is rotatably mounted on the gear cover.

### Claim 13 (depends on 1)

The torque wrench of claim 1, wherein the second pinion gear engages the first pinion gear via at least one intermediate gear.

### Claim 14

A position sensor assembly for use in a system in which a first beam moves relative to a second beam, comprising:
a first position sensor portion mounted on the first beam, including:
a first pinion gear;
a second pinion gear operatively engaged with the first pinion gear; and
a position sensor engaged with the second pinion gear to sense an amount of displacement of the first beam relative to the second beam; and
a second position sensor portion mounted on the second beam, including:
a rack gear operatively engaged with the first pinion gear of the first position sensor portion.

### Claim 15 (depends on 14)

The position sensor assembly of claim 14, wherein the first position sensor further includes a gear cover having an input portion to receive an end of the first beam; and wherein the first pinion gear and the second pinion gear are rotatably mounted on the gear cover.

### Claim 16 (depends on 15)

The position sensor assembly of claim 15, further comprising a spring having a first end coupled to the first beam, and a second end coupled to the second pinion gear to push the gear cover against the rack gear.

### Claim 17 (depends on 14)

The position sensor assembly of claim 14, wherein the first pinion gear has a larger diameter than the second pinion gear.

### Claim 18 (depends on 14)

The position sensor assembly of claim 14, wherein rack gear is a straight gear.

### Claim 19 (depends on 14)

The position sensor assembly of claim 14, wherein the position sensor is a potentiometer that generates an electric signal indicative of an amount of displacement of the first beam relative to the second beam.

### Claim 20 (depends on 19)

The position sensor assembly of claim 19, wherein the potentiometer is a rotating potentiometer, and wherein the rotating potentiometer and the second pinion gear are disposed on a common axis.

### Claim 21 (depends on 14)

The position sensor assembly of claim 14, wherein the position sensor engages the second pinion gear via at least one intermediate gear.

### Claim 22

A torque wrench, comprising:
a main beam having a distal end and a proximal end;
a ratchet head disposed at the distal end of the main beam;
a handle assembly disposed at the proximate end of the main beam;
an indicator beam having a first end fixedly secured to the main beam at a first location on the main beam, and a second end;
a position sensor assembly disposed at a second location on the main beam to detect an amount of flexure of the main beam relative to the indicator beam in response to a torque applied to the handle assembly, the position sensor assembly including:
a rack gear secured to one of the main beam or the indicator beam;
a pinion gear mounted on a first axis secured to the other one of the main beam or the indicator beam, wherein the flexure of the main beam causes movement of the rack gear relative to the first pinion gear; and
a position sensor disposed away from the first axis to generate an electrical signal indicative of the amount of flexure of the main beam relative to the indicator beam based on the movement of the rack gear relative to the pinion gear.

### Claim 23 (depends on 22)

The torque wrench of claim 22, wherein the pinion gear is a first pinion gear, and wherein the position sensor assembly further includes a second pinion gear mounted on a second axis secured to the other one of the main beam or the indicator beam, and in geared connection with the first pinion gear; wherein the position sensor operatively engages the second pinion gear.

### Claim 24 (depends on 23)

The torque wrench of claim 23, wherein the position sensor includes a rotating potentiometer disposed on the second axis.

### Claim 25

A torque wrench, comprising:
a main beam having a distal end and a proximal end;
a drive element disposed near the distal end of the main beam;
an indicator beam having a first end fixedly secured to the main beam at a first location on the main beam, and a second end;
a position sensor assembly at least partially disposed at a second location on the main beam to detect an amount of displacement of the main beam relative to the indicator beam, the position sensor assembly including:
a straight rack gear secured to one of the main beam or the indicator beam, wherein the straight rack gear includes a plurality of teeth aligned along a substantially straight line;
a pinion gear in geared connection with the rack gear and secured to the other one of the main beam or the indicator beam;
a spring having a first end coupled to the first beam, and a second end, wherein the spring pushes the pinion gear against the straight rack gear; and
a position sensor engaged with the pinion gear to sense an amount of displacement of the main beam relative to the indicator beam.

### Claim 26 (depends on 25)

The torque wrench of claim 25, wherein the pinion gear is a first pinion gear; and wherein the position sensor assembly further includes a second pinion gear in geared connection with the first pinion gear and coupled to the second end of the spring.

### Claim 27 (depends on 25)

The torque wrench of claim 25, wherein the position sensor engages the pinion gear via at least one intermediate gear.