Autogard backlash-free safety couplings work as spring-loaded positive couplings. The special roller or ball guides guarantee a totally backlash-free transmission of the torque in both directions of rotation. 

The couplings are therefore especially suitable for use in speed and direction controlled drives in conjunction with a closed control loop.

Uniform loading of the rollers and balls guarantees high system stiffness, which is important especially for modern servo drives. 

The roller or ball guides simultaneously guarantee high reliability and switching frequencies when used with high dynamic servo drives.

Cylindrical roller Locking Element for low, medium and high dynamic loads Suitable for types 1,2,3,5,6

Ball style Locking Element for low and medium dynamic loads Suitable for types 7, 8, 9, 10

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In the event of an overload the rollers or balls move out of the guides (see figures 1 and 2). This results in an axial movement, which activates a proximity switch or limit switch that immediately makes contact to switch off the drive. To avoid damage to the safety coupling, the drive must be switched off immediately after an overload. Autogard backlash-free safety couplings were developed for especially dynamic drives operated under constantly changing directions of rotation and under high acceleration.

Figure 1 Roller principle Figure 2 Ball principle

The safety couplings work exclusively with specially selected disk springs with a pronounced digressive characteristic (see figures 3 and 4). This advantage guarantees shortest switching times (2 – 4 msec) and a low residual torque, less than 5% in a disengaged state. The coupling disengages immediately when the cut-out torque is exceeded.

Figure 3

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Figure 4

The torque drops immediately to a small residual value, typically 2 to 5%. The switching work required of our couplings corresponds to only a fraction of that of conventional safety couplings with progressive characteristic (see figure 3). This is a decisive advantage because even ultra-short surges in speed are rendered harmless by the safety coupling.

Adjustment of the cut-out torque:

Autogard backlash-free safety couplings are delivered with set cut-out torque. There are two possibilities for this, namely:
1) The user / operator names the cut-out torque in his order.
2) The coupling is set on the lowest cut-out torque in its torque range.

Figure 5 shows the spring travel we use for our safety couplings.
Point A stands for the highest spring force = highest cut-out torque.
Point B stands for the lowest spring force = lowest cut-out torque.

Note! The spring travel corresponds approximately to three-quarters of a revolution of the set collar. Every required cut-out torque is progressively adjustable.

Figure 6