Index drives are used to start and stop a table, conveyor, or other piece of equipment at precise intervals. Index drives are designed using the mathematical laws of motion to create smooth, jerk free movements from one position to another along a production line. As a result, index drives allow a line to accelerate or decelerate in a controlled motion from one station to another in either a clockwise or counterclockwise direction. Standard index drive designs allow for a predetermined number of stations, from a minimum of two up to 36. Index drive stations are generally set at 20, 40, 60, 120, 180 degrees, and so on. Index drives are used in assembly, packaging, finishing, and other manufacturing procedures.
The types of index drives include cam index drives, ring index drives, and roller gear index drives. A cam index drive is best used when ultra high speed indexing is needed. The design of cam index drive eliminates the reversal of roller follower direction and removes the tendency to overheat and inflict unwanted tear on cam surfaces. High rates are possible with cam index drives (more than 1,000 indexes per minute), thus allowing for high torque and high load capabilities. Cam index drives are not appropriate for a large number of stations (one to eight are feasible). A ring index drive features larger through-holes to accommodate a variety of automated machinery and equipment, including electrical wiring and air or hydraulic lines. The large center through-holes free up the outer periphery for greater access and additional equipment. Ring index drives are more suited for automatic assembly machinery with a large number of workstations. Roller gear index drives are most appropriate for compact and low profile situations. A roller gear index drive offers motion flexibility, through-hole capability, and a 2 to 24 station range. A roller gear index drive is best used when medium to high torque and a right angle shaft orientation are required. Roller gear index drives can also be used in harsh environments that need torque limiting protection.