Tangen Drives - Precision-Built Drives Convert Continuous Motion into Precise Intermittent Motion

Specialists in Intermittent Motion

Precision-Built Drives for Converting Continuous Motion into PRECISE INTERMITTENT MOTION

Tangen Drives, based in Clearwater, Florida, was founded in the 1960's, it was known as Geneva Motions Corp. Tangen Drives has used an engineering development based on a long and industry-proven Geneva motion principle. The radial center of each slot is tangent to the circular path of the exact center of the driving cam, resulting in consistent and smooth acceleration and deceleration patterns of the wheel.

In mid-year 2000, Johnson's Services Two Inc. (JSII), recognized Tangen Drives for its superior Geneva mechanism, providing repeatable indexing to the same position. Follow through with the same quality and precision of the Geneva wheel and drives known as a Tangen Drive, JSII completed its acquisition in October 2000 keeping the same experienced and qualified personnel for the operation. JSII committed to quality and pride for converting continuos motion into precise intermittent motion.

JSII has also committed to improvement of its customer service staff to increase response time to our customer base. In today's fast paced environment, the improvement was critical to the success of Tangen Drives. This web site gives a brief overview of our product line. For more information, please request a copy of our catalog.

The Tangen Drive is a rugged, precision-built drive for converting continuous motion into precise intermittent motion.

The Tangen Drive consists of a constantly rotating driver and a driven wheel. The wheel may have 4, 5, 6, or 8 precision-machined radial slots. A matching cam follower, mounted on needle bearings on the driver, engages on of the slots on each revolution of the driver, thereby indexing the wheel. The concave section between the slots is precisely machined to mate with the locking hub on the driver, to prevent movement of the wheel during dwell.

Standard-design Tangen Drives have one cam follower on the driver; special-design units having more than one cam follower are available at extra costs.

The Tangen Drive is a new engineering development based on the long-known and industry-proved Geneva motion principle. The Tangen Drive derives it name from the fact that the radial centerline of each slot is a tangent to the circular path of the exact center of the driving cam follower. Each Tangen Drive is accurately generated to this specification, resulting in a smooth, sliding contact between cam follower and slot walls that provides a consistent acceleration and deceleration pattern.

1. Cam follower enters the slot dead-center, since the radial centerline of the slot is a tangent to the path of the center of the cam follower.

2. With smooth, sliding contact, cam follower accelerates the angular velocity of the wheel. Notice that at this point, the locking hub is free of the wheel.

3. At mid-point of index, angular velocity of wheel reaches maximum. Cam follower rolls smoothly in precision-machined slot on friction-free needle bearings.

4. At end of index, cam follower leaves slot and locking hub engages recess in wheel in demonstration of ingenious engineering and close-tolerance machining.

5. During dwell, precision-machined locking hub on drive positively prevents motion of wheel in either direction, to maintain wheel position and assure indexing accuracy.

Geneva Wheel or Geneva indexing
The driver wheel consists of a locking radius and a cut out for a pin (Tangen Drives uses cam followers for smoother movement). Geneva wheels use this pin to index the slotted wheel to its next position and then have the locking radius to hold it in position until the driver wheel makes the next revolution to again start the mechanical index.

The principle is the same for a Geneva wheel. A gear by definition is a toothed wheel or disk designed to mesh with another to control the motion of another. Normally thought of as gaining speed or reducing speed. The Geneva gear or Geneva mechanism has the same principle but stops at a point then indexes to the next. By having slots instead of teeth, the cam follower or pin is used to control the motion of another.

Movement can be described as the act of moving one body or part to another body or part. In our case of Geneva movement, the drive (figure b) wheel is the movement which acts upon the Geneva indexing plate (figure a) to start it moving or mechanically indexing to the next position and then locks or sets the dwell position.

Tangen Drive derives its name from the fact that the radial centerline of each slot is a tangent to the circular path of the exact center of the driving cam follower. This provides smooth motion.

Geneva motion or Geneva control can be described as an act or process of movement or passage of a body from one place to another. This is accomplished by a constantly rotating motion and changing it to intermittent motion. This movement is relevant to the number of slots and radius. The possibilities could be from three up to twenty-four stations. The drive (figure a) one revolution moves the driver wheel 1/3 of a revolution or 120 degrees where four station wheel moves 1/4 turn or 90 degrees, up to the 24 station drive. To come up with the degree of turn, simply divide the number of slots into a circle, (360 degree).

The original Geneva device was used as a control to avoid over winding a watch or music box in Geneva Switzerland, hence the name Geneva. Later the process was use was in film process. In current uses they are used in wide variety of motion control from indexing mechanical tables, conveyors, valves parts and many other mechanical uses of controlling timing or motion.

Geneva positioning is when the driver wheel (figure a) positions the Geneva wheel (figure b) to the desired location. If the number of dwells or stops are six, then the revolution of the wheel (figure b will be 1/6 turn or 60 degree of turning these numbers are in the chart on this web site both in “Series S” and “Series R”. You can get a relationship of index time and dwell time by dividing the index time into 360 degrees and the dwell by 360. Example a four station Geneva assembly’s index time is 90 degrees and the dwell time of a Geneva assembly is 270 degrees. 360/4=90 90-360=270 You can obtain a percentage of timing by dividing 90 degrees into 360 which gives you an index time of 25% and by dividing the dwell time of 270 degrees Into 360 degrees, this gives you seventy five percent times dwell. . If your input speed is 4 RPM then 25% of four seconds is one second index time and Seventy five percent of the four seconds is three seconds of dwell time.

The rotating wheel that interlocks and indexes the Geneva wheel is referred to as the driver. We can look at the driver as a cluster speed that can turn either direction and is converted into precision intermittent motion with correct machining (engineered by Tangen Drives). In order to hold the dwell, it is important to have the locking radius machined to the recess in the wheel. (Figure b) To hold dwell and positioning this radius and recess must be very close. This is standard operating procedure for all Tangen Drives wheel assemblies. Refer to the Series S and Series R The above mentioned units have a backlash adjustment when used in a CR or MR units. (See products page) The backlash adjustment is provided by the use of eccentric mounting of an oil light bearing in the MR Unit and the CR unit bearing housing on the input shaft. This is eccentrically mounted to permit adjustment to compensate for wear on the drive wheel caused by extended service.

The indexing of a Geneva assembly can also relate to how it works on a rotary table. In relation to how far the table turns or indexes or how many operations are needed to complete the assembly of the item/items. Geneva indexing has multiple applications, conveyor systems where the conveyor needs to stop at the same place or move a specific amount of length every time, movement to operate hydraulic valve, or water flow valves. Sometimes instead of moving conveyer or table you may index an assembly (move or index a different operation to a part, i.e., welding painting nozzle air flow or electrodes to perform tests, etc.) This application can be more varied and are many more then mentioned above. The Geneva systems described above can be referred to as rotary to reciprocating motion and dwell mechanisms, indexing or intermittent mechanisms, automation devices automation mechanisms, timing devices mechanical positioning devices, driven positioning, mechanical indexer repeatable precise indexing motion control devices or components.