Pneumatic Indexing Drives
Pneumatic indexing drives, such as our indexing actuators, are simple, mechanical components capable of repetitive rotary indexing with no accumulating error. They are based on rack-and-pinion rotary actuators with the addition of one-way roller clutches and a ratchet and pawl system for stopping and registration. The motion is initiated by a directional control valve, so they are well suited to flexible automation where the index must occur on demand. They are robust and durable, but cannot match the controlled motion characteristics of the servo or cam drives.
PROS:
- Low cost
- Very simple to design, implement, and maintain
- Robust construction can support the rotating load with its own bearings
- Operate in harsh environments
CONS:
- Poor dynamic control of load
- No programmability
- Air consumption (only when moving)
Energy Consumption
The relative amount of energy these drives consume will depend on the duty cycle of the application. Cam and servo drives are both quite efficient but differ in that the servo uses full power to hold the load in place whereas the cam drive uses power only when driving the load. A pneumatic indexer uses compressed air, which is less efficient than an electric motor drive, but also uses no power when in the locked condition. So, if the duty cycle includes a high percentage of dwell time, the advantage shifts toward the cam and pneumatic systems.
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