A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque.
Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine.
Geared devices can change the speed, torque, and direction of a power source.
The most common situation is for a gear to mesh with another gear, however a gear can also mesh a non-rotating toothed part, called a rack, thereby producing translation instead of rotation.
Gear Types & Gear Information
The teeth of a bevel gear may be straight-cut as with spur gears, or they may be cut in a variety of other shapes. Spiral bevel gear teeth are curved along the tooth's length and set at an angle, analogously to the way helical gear teeth are set at an angle compared to spur gear teeth. Zerol bevel gears have teeth which are curved along their length, but not angled. Spiral bevel gears have the same advantages and disadvantages relative to their straight-cut cousins as helical gears do to spur gears. Straight bevel gears are generally used only at speeds below 5 m/s (1000 ft/min), or, for small gears, 1000 r.p.m.
Measuring and Evaluating Gears on a Coordinate Measuring Machine
Leitz measuring machines, Leitz probe heads and QUINDOS software are designed to inspect any geometry, including any kind of gear or gear cutter, without a rotary table.
Using only three axes instead of four means:
Better system accuracy, especially for the inspection of large and heavy gears Higher throughput due to pallet measurements Easy set up, no centering or alignment of the gear required Less investment and less maintenance costs.
Software certification: QUINDOS Gear software is certified by the PTB (Physikalisch-Technische Bundesanstalt) of Germany.
Gear standards: Evaluations according ISO, DIN, AGMA, JIS and CNOMO, all included in the QUINDOS Gear basic package. Also available is gear evaluation according to Caterpillar standards.
- Small and medium size gears: comparable to a dedicated gear measuring machine.
- Large and heavy gears: Leitz gear inspection centres do provide better accuracy because no rotary table is used.
Gear inspection with Leitz measuring machines
- Small gears: similar to a dedicated gear checker but much higher throughput with pallets.
- Large and heavy gears: faster than a dedicated gear measuring machine because the gear does not need to be turned.
- Flexibility: If your Leitz gear inspection centre has some idle time, you can use it as a high precision coordinate measuring machine to inspect just any component.
High-precision Leitz measuring machines are also used as gear inspection systems.
They can measure not only any kind of gear but any complex gear cutting tool as well.
Due to their unique design concept and due to the software capability of QUINDOS, the Leitz gear inspection centres offer some decisive advantages compared to a conventional dedicated gear tester.
Gear inspection using pallet strategy
There can be any number of gears and/or cutters which can be placed on a pallet, the number is only limited by their size.
The pallet is then loaded onto a Leitz gear measuring machine and all gears or cutters are measured fully automatically, without the need for an operator, just push a button and let it run.
Gear inspection using a pallet strategy gives the following advantages:
Measuring gear segments with a CMM is straight forward:
- Unbeatable throughput of gears
- Much less costs of inspection
- No operator required
Very large gears are usually produced in several segments, and conventional gear inspection systems cannot measure such segments.
For Leitz gear inspection centres it does not matter if a gear is complete or cut into segments.
QUINDOS Gear software can put the measured segments together and evaluate them as if measured in an assembled condition.
The picture shows a simulation of a Leitz PMM-G 60.40.16 measuring all four segments of a gear in one set up. The gear diameter was 5000 mm.
Measuring gears on very long shafts:
The maximum length of a gear shaft which a dedicated gear tester can inspect is defined by its Distance between Centres.
Leitz gear measuring machines can measure a gear shaft in vertical as well as in horizontal clamping. Therefore even gears on shafts several meters long can be measured easily.
Measuring gear racks:
Gear racks of any size and length can be measured on Leitz gear inspection centres as they do not require a rotary table for gear inspection.
The rack can be put anywhere within the measuring volume.
The software options QUINDOS Gear and QUINDOS Curves are needed to inspect gear racks.