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R+W Precision Safety Couplings

Learn about the basic design, function, and handling of R+W ball-detent torque limiters and safety couplings, including how to properly adjust the disengagement torque value, and re-engage fully disengaging versions.

Topics:
Aerospace Automation Motion Control Robotics

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    Transcript

    00:00:07 r&w designs and produces a wide variety of backlash free ball detent safety couplings offering Precision torque overload protection and preventing equipment damage and downtime in the event of a machine malfunction due in part to a patented internal preload and a special spring characteristic r&w safety couplings are often capable of reacting much more quickly and

    00:00:27 accurately than electronic controls in preventing mechanic overloads here we'll be covering how they work available configurations adjustment of the disengagement torque setting and handling of fully disengaging types r&w safety coupling start with a precision machine clutch base and a series of hardened steel Drive balls the

    00:00:49 balls are retained in an array of holes around the perimeter of the clutch base and braced on one side by a machined ring situated between two rows of ball bearings as an output flange with conical detents to fit over the drive balls the outer row of bearings is covered by a retaining ring and held in place by a snap ring one or more disc Springs are placed against the ring

    00:01:11 which braces the drive balls on the other side and pressed against the ring by a spanner nut which threads onto the clutch base finally a means of locking the safety coupling to a shaft is included which in this case is shown as a clamping bushing the output flange is fitted with either a flexible shaft coupling or another Drive connection device such as a gear roller chain

    00:01:31 sprocket or timing belt sprocket under normal conditions the assembly stays locked together to transmit motion and torque with zero backlash when an overload occurs the conical detents of the output flange push the drive balls out against the spring plate causing the drive line to disengage a proximity sensor is often used to detect the actuation and Signal the control unit to

    00:01:53 stop the machine one of the key components in r&w safety couplings is the disc or Belleville spring use of this spring not only lends itself to making the safety coupling more compact but more importantly it facilitates a faster disengagement than if traditional coil springs were to be used this is because the Springs function in the digressive range where the spring

    00:02:14 provides decreasing resistance the more it is flattened or deflected looking at this chart from left to right it can be seen that as the disc spring is first pushed it provides increasing spring Force resistance but after a short distance the spring Force resistance begins to decrease and continues to decrease with more deflection all the way through the release or actuation of

    00:02:35 the safety coupling the result is a spring-loaded device which is highly sensitive during actuation facilitating this engagement within just a few milliseconds of aise and torque r&w safety couplings can be configured for four distinctly different behaviors upon disengagement single position multi-position load holding and full disengagement most commonly used is

    00:02:57 the single position automatic re-engagement version where the drive balls and detents are arranged in a pattern which only allows for re-engagement once per rotation a light residual spring Force remains when the coupling is disengaged causing the drive balls to drop back into their detents for automatic re-engagement once the torque and rotational speed have been

    00:03:16 reduced the multi-position automatic re-engagement version has the drive balls and detents arranged in a pattern which allows for re-engagement every 60° special options offer re-engagement every 30 45 90 and 120° the load holding version is a specialty variety which only disengages the load for a few degrees of free rotation before internal teeth engage

    00:03:39 blocking the coupling from freely spinning often referred to as an overload detection device the load holding version is for specialty applications contact r&w for more information another widely used configuration is the full disengagement version upon disengagement the disc spring snaps through its Center fully removing spring pressure from the drive

    00:03:59 balls and allowing the coupling to rotate freely until manually reset this type is useful for situations where the drive motor cannot be stopped immediately or is rotating at a relatively high speed prior to disengagement the standard engagement interval is every 60° single position patterns are also available basic designs include flexible Bellos

    00:04:19 couplings with clamping collars flexible Bellos couplings with conle clamping bushings rigid safety couplings for attaching Drive sprockets and gears and vibration damping elastomer couplings to name a few r&w safety couplings are inscribed with disengagement torque values corresponding to the appropriate location of the torque adjustment nut an

    00:04:41 adjacent marking serves as a reference against which to check the nut location to adjust the disengagement torque setting first loosen the Locking screws holding the torque adjustment nut in place in some cases there is a single clamping screw in place of the three set screws shown here next turn the adjustment nut with a spanner wrench to the desired location because of the

    00:05:02 digressive spring characteristic backing the nut away from the spring set increases the disengagement torque and turning the nut toward the spring set decreases the disengagement torque when adjusting the disengagement torque setting it is important to stay within the range marked on the adjustment knot turning too far will result in loss of functionality once the desired

    00:05:22 disengagement torque setting has been reached rescure the adjustment nut to avoid unintended movement during operation [Music] full disengagement type safety couplings completely disconnect the drive line upon overload unlike the other configurations with this type the spring set snaps through its Center fully

    00:05:42 removing spring pressure from the drive balls and allowing the coupling to rotate freely until stopped and manually reset to re-engage line up the reference markings on the two respective sides of the safety coupling using a pair of Flathead screwdrivers against the step in the adjustment nut press against the spring set to snap the coupling back into engagement the coupling is

    00:06:04 re-engaged and ready to run r&w safety couplings offer the best in mechanical torque overload protection providing a fast and accurate disengagement in the event of a malfunction contact r&w with your safety coupling requirements and get the ultimate connection worldwide [Music]