The machine builders drive chain that can push as well as pull

"At first glance it seems like a contradiction: but it is actually an ingenious solution in linear drive technology" says Hertfordshire based R A Rodriguez, through whom Grob LinearChain is now available in the UK

The company states that LinearChain offers “endless” possibilities over other drive solutions such as traditional chains which can only pull, and cylinders, which (unlike LinearChain) need to retract a distance equivalent to their length. A combination of cylinder and chain without the disadvantages mentioned would be ideal, hence the development of LinearChain. 

The product consists of specially formed, high-precision mechanical chain links that engage positively with one another to provide mutual strength and support (as a rigid unit), thus facilitating both a pull and a push capability. Importantly, LinearChain is a purely mechanical movement actuator and is thus said to be environmentally friendly, reliable and requiring little maintenance. Stroke lengths of up to 30m are easily achievable says Rodriguez, who cite many successful LinearChain applications. One of these is for lifting. Applications such as table and platform lifts benefit from the space-saving and easy positioning attributes of the product. Stroke forces of up to 35kN are possible with a single chain, a factor that also makes the solution suitable for other types of lifting system, including scissor lifts and columns. Often, a single motor is sufficient to drive two parallel LinearChains says the supplier

A recent customer project saw a LinearChain installed in a lifting column with a length of 6m for the safe transportation of heavy loads between building floors. Two directional changes of the LinearChain through 90° enable parallel storage of the chain in the system. Consequently, installation engineers could either mount the lifting column directly as a free-standing unit on the floor, or with additional fastenings to the ceiling or wall without requiring further space for chain storage. Ultimately, LinearChain ensures the lifting column can position large loads precisely within constricted space conditions. Systems that require horizontal motion can also gain from the adoption of LinearChain according to Rodriguez. A case in point is the provision of infeed and outfeed motion to an industrial washing machine for pharmaceutical transit boxes. In another example, LinearChain is aiding the transfer of shipping containers from rail to road transport, and vice versa. This operation takes place in under 3 minutes without the need for either a crane or a forklift. Further recent applications highlighted include the forwarding of workpiece loads in and out of a heat-treatment furnace, and the use of LinearChains (attached to a plunger) for pressing raw tobacco into transport containers. The latter takes place at a stroke speed of 300mm/s.

Rodriguez says that LinearChain is also finding favour at a number of automotive OEMs, with one plant using the product for an engine marriage system. This system features two tables, each of which lifts and lowers using a LinearChain with 35kN lifting force and 2m stroke length. The first table lifts and engages its pallet with a front-end engine assembly from the plant’s monorail system, before the table lowers and the engine transfers to the second table via a conveyor. Subsequently, the second table raises up from where two line workers guide the engine into the car and secure it in place using nut-runners. While this is taking place, the empty pallet returns to the first table via a second conveyor.  

Thanks to high positioning accuracy, constant stroke speed and shock-free motion with no elastic hysteresis under load, the potential uses for LinearChain are said to be virtually endless. Some of the more unusual projects to date have involved the movement of flower boxes in commercial greenhouses, clearly a growing aspect of the business and taking centre stage with lifting equipment in theatres.