John Crane has launched a new power transmission coupling. The new Metastream M Series ZMH flexible membrane coupling improves on John Crane’s existing ZMC coupling and is specifically intended for cooling tower installations. The corrosion-resistant ZMH has been designed to withstand the hot, humid and hostile environments typically found in cooling towers and to improve on the performance provided by its predecessor. Designed for infinite life, it has no wearing parts, requires no lubrication and so represents a genuine fit-and-forget solution. The ZMH incorporates a stainless steel radial spoke membrane. The ZMH’s low restoring forces under misalignment and high power/weight ratios minimise the imposed loads on critical machinery components such as bearing and seals. In the rare event of a membrane failure, the ZMH’s failsafe design will disconnect the machinery but also retain the composite-fibre spacer in place in order to avoid damage to adjacent components. The result is a loss of cooling effect, rather than potentially severe and expensive machinery damage. Light in weight and able to accommodate shaft separation distances of up to 20ft without the need for an intermediate bearing, the ZMH can be installed before or after the shaft has been aligned. It can also be removed without disturbing the connected machinery.