The use of mechanical torque limiters is often considered to be outdated by those who prefer to control torque overload through electronic current limitation.  While this is effective in many cases, as machinery becomes more dynamic, the inertia of moving parts becomes more critical.  It is indeed possible to abruptly decelerate a rotating mass through unintentional blockage or application of a dynamic braking system at a faster rate than the drive would normally accelerate.  This creates torque overload through reflected inertia which is completely independent of the electronic system, and can easily exceed the peak torque rating of the motor.  While older and bulkier designs may be out of the question, these modern mechanical torque limiters offer a high level of sensitivity and accuracy, with increasingly smaller impact on the size, mass, balance, and power consumption of the drive system.

The SL Series uses the proven spring loaded ball detent system, along with a previously patented preload for zero backlash operation.  But to achieve its target of 50% weight reduction, R+W embarked on a two year collaborative effort with local universities, designing the product from the ground up rather than simply redesigning or optimizing existing products.  The result is a torque limiter constructed from state of the art materials with unique surface treatments and innovative assembly technology – surpassing weight reduction targets and simultaneously reducing its footprint.  One example of this newly achieved size reduction is a torque limiter rated to disengage at 160 Nm, which in the past would have had at best a mass of 1.3 kg and a moment of inertia of 1.6 * 10^-3 kgm², now weighs 370 grams with a moment of inertia of 0.8 * 10^-3 kgm².  What that amounts to is an automatic torque limiter with unparalleled power density on planet earth.

In addition to custom material specifications, specially designed spring systems, and some improvements to the ball detent configuration, resulting in a 40% increase in torque capacity for a given size, the weight reduction was also achieved through the compression of individual components. This, of course, is without negative impact on the precision or service life of the torque limiter.  The SL Series, just like the previously existing R+W torque limiter designs, can handle in excess of 10,000 disengagement events, depending on rotational speed.

The four sizes (Series 30 / 60 / 150 / 300) cover disengagement torque values from 5 Nm to 700 Nm, and involve various mounting options, including both direct and indirect drive versions.   Models SLN (clamping) and SLP (keyway) attach by flange to sprockets, sheaves, pulleys, and gears, and include an integral dual bearing system to support belt and chain tension when properly located over the shaft.  Models SL2 (bellows coupling) and SLE (servo insert coupling) mount inline between two independently supported shafts, such as motor to ball screw connections, and compensate for the small but inevitable misalignment which exists in this type of machine layout.  All four types are field adjustable, and come with both English and metric bores according to customer specifications.

The SL Series gives everyone who has overlooked this type of device due to size or weight considerations a chance for a second look.  Contact R+W today with your requirements and realize the benefits of working with the ultimate coupling, worldwide.

R+W America
www.rw-america.com

Schmidt Offset couplings deliver precision for parallel offset shafts. They transmit constant angular velocity and torque in a range of parallel shaft misalignments. They are used in a range of machine applications including printing, embossing, paper converting, pharmaceutical, and automated assembly systems.

The new Schmidt sealed bearing coupling feature incorporates needle bearings with internal micro-poly lubrication. There are no lube fittings making for a cleaner coupling setup. Compact in design, Schmidt Offset couplings with the new zero maintenance bearing option keep out contaminants and foreign matter, enabling the couplings to be used in less than ideal operating environments.

Schmidt Offset couplings are designed to handle high amounts of parallel offset up to 17 in. and are available with torque capacities up to 459,000 in.-lbs. They impose no side loads on shafts or bearings and eliminate radial shaft vibrations.

Zero-Max
www.zero-max.com

These special couplings are precision machined with a thermally and chemically stable, wear resistant, polyurethane insert press fit between the two for zero backlash.  A smooth fit between the insert and the hubs helps the insert to compensate for lateral, angular and axial shaft misalignment.  The insert is impregnated with graphite, giving it electrically conductive properties, eliminating the potential for any charges arcing from one hub to the other.  Official serialized markings including the part number are required by the directive and are clearly visible on each unit.

These precision couplings are available in a variety of mounting configurations, and can include torque overload protection.  There are nine total sizes ranging from torque ratings of 2 – 2150 Nm (17 to 19,000 in-lbs).  Both English and metric bore diameters are available in a range from 3 – 80 mm (1/8 to 3.125 in.) with or without keyways.

R+W America
www.rw-america.com

The SCXW is a Double Disc type precision disc clamping coupling with high torque but no backlash.  Its torsional rigidity is up to 26% higher than conventional (standard) disc clamping couplings. It suits applications requiring fast positioning precision.  All the bolts are trivalent chromate plated and suitable for use in clean environments.

The MFJGWK is available as a high rigid Oldham coupling, set screw type. The MFJCGWK is a high rigid Oldham coupling, clamping type.  Both products feature an aluminum bronze spacer and have a keyed bore.  These couplings have allowable torque 2X higher compared to resin spacers.

The SCOC is a short Oldham coupling, clamping/spacer type. This space-saving version works with miniature devices because it is 17% shorter than conventional types.

Most MISUMI Couplings ship in six days, with the exception of the new High Rigid Oldham Couplings, which ship in eight days.  Some couplings offer optional express shipping for faster delivery.

MISUMI USA, Inc.
Http://us.misumi-ec.com

The Hybrid Connector can simplify connections in a range of applications including diagnostic equipment, surgical tools, analytical instrumentation and hospital beds. The easy-to-use connector also can be customized for specific customer applications.

Colder Products Co.
www.colder.com

The 2009 BK series catalog from R+W represents the latest collection of standard bellows coupling designs for applications requiring torque ratings from 15 Nm – 10,000 Nm. Flanges, shafts, hollow bores and nearly any other mechanical interface are accommodated.

R+W America
www.rw-america.com

PTMotion GmbH
www.ptmotion.de

Belden Inc.
www.beldenuniversal.com

Ruland Manufacturing Co. Inc.
www.ruland.com

Ringfeder Power Transmission USA Corporation markets a range of power transmission components and keyless shaft/hub technology.  Other power transmission products include shock absorbing devices, flexible elastomeric couplings, flexible disc couplings and torque limiters along with other specialty and custom made products.

RINGFEDER

www.ringfeder.com

Available with split clamping collars or keyway and set screw connections, the three new body sizes allow for backlash free, vibration damping power transmission, paired with strong torque density. Dual flexture and jack shaft versions are also available for spanning longer distances and compensating for larger misalignments. Unlike the pre-existing range of R+W elastomer couplings, which use a single spider element between the new hubs, the new larger sizes will use individual vibration damping compensation elements to fit between each mating set of coupling teeth. These couplings are available in English and metric bore diameters up to 170 mm.
R+W America
www.rw-america.com