Cam-clutches provide protection overrun in fans and air conditioners

Paul Boughton
A special design of lift-off cams that ensures precise backstopping and optimised speed while overrunning without further contacts between cams and races.

Tsubaki has launched its new range of MREU (Motor Reducer European) cam-clutches, which are designed for back-stopping operations in light duty applications at high RPM: typically in fans, air conditioning units and ventilation systems.

The new clutches are designed primarily for OEM applications and are competitively priced with a special design of lift-off cams that ensure precise backstopping and optimised speed while overrunning without further contacts between cams and races.

The MREU series clutches have been introduced to meet the requirements of European machinery and Heating & Ventilation installations.

Although extremely compact, they integrate a full complement of cams to provide the maximum number of load transmitting members for a given diameter. This results in a greater torque capacity, size-for-size, than other cam clutches, and longer fatigue life.

The cams in the MREU Cam Clutch are lift off type, offering the advantage that they are designed to lift off and have no contact with the inner and outer races of the clutch whilst it overruns. This feature offers benefits in terms of zero friction, longer wear life, and the facility for high speed overrunning.

A typical application of the MREU cam-clutch is extraction fans. These units can suffer heavy damage if they are rotating in the reverse direction as a result external air currents, when the drive motor is switched on.

The MREU clutch can prevent this problem with its backstopping function, reverse rotation being prevented by instantaneous automatic engagement of the clutch.

Another typical application is for manufacturers of Air cooling fans where fans in the same vicinity do not always operate simultaneously. In this situation, the convection of air current from one fan can make another in close proximity start to slowly rotate in the opposite direction causing component damage or in some cases failure of the reducer or coupling units. The benefits of using a cam clutch in this type of application means selective operation or function can be achieved, thus reducing repair cost and, importantly, energy costs.

The cam clutches are designed for convenient press fit in housings. They are manufactured in a range of capacities and styles which offer the best functional characteristics for performing general overrunning, indexing and backstopping.

Lube-free benefits

Tsubaki is providing all the non-lube, low maintenance benefits of its well proven Lambda chain in a heat resistant version that has an operational temperature range from 150°C to 230°C. The new heat resistant Lambda shows no degradation at high temperatures and offers over four times the wear life of standard RS50 chain at 230°C.

The launch of H.T. Lambda extends the lube-free, elongation-free characteristics of Lambda chain into applications such as heat sealing in packaging, semiconductor production, dry and steel furnaces and die casting - for components such as automotive parts. Previously these processes would have been served by standard chains with special coatings, which were both costly and did not offer good wear life.

Tsubaki's H T Lambda overcomes this problem, as its design is a proprietary one purely for high temperature operation. This offers many advantages, not least that, unlike standard chain, H T Lambda does not have to be derated for high temperature operation, due to chain rollers and plates losing their strength. To account for this problem standard roller chain generally has to be much larger when used at higher temperatures. As a result, it is more costly, takes up more space and uses more energy to transmit the same power as the H.T. Lambda chain.

In tests performed in a 2300C environment, Tsubaki's H T Lambda chain achieved over four times the wear life of RS50 standard chain and about three and half times the life of Tsubaki's standard Lambda chain, which is not designed for high temperature operation. Importantly, although the standard chain showed degradation at this high temperature, H T Lambda did not.

The lube free performance of H T Lambda at high temperatures is the result of a construction that employs special oil impregnated bushes. These provide stable lubrication and anti-wear properties for the chain at high temperatures. The design also employs specially coated pins, solid rollers and inner plates that are coated with nickel. HT Lambda employs NSF H-1 Food Grade lubricant, ideal for applications where it is an industry requirement.

In addition to its high temperature performance, H T Lambda is part of Tsubaki's eco-friendly chain group and has undergone a life cycle assessment LCA. This is a systematic evaluation of the environmental aspects of the product through all stages of its life cycle, from raw materials to waste management, including recycling and final disposal. With the majority of Lambda chains the LCA has revealed real ecological benefits, with CO2 emissions reduced by 89.4 per cent.

Tsubaki UK Ltd is based in Nottingham, UK.