Mechanical gear change provides two-speed option

Edited by the Engineeringtalk editorial team Feb 15, 2002

A novel plug-in mechanical gear change option provides a cost-effective two-speed facility for a wide range of applications.

The Type RC mechanical gear change is available as an option on the Series 2000 planetary gearbox from Reggiana Riduttori.

Installed on the input side of its linear reduction gears and fully integrated into the unit, the two-speed selector is available from only GBP 500.

Ideal for applications requiring both high speed/low torque and low speed/high torque modes of operation, it also has considerable potential as a disconnect mechanism, by using the neutral position.

Already the winch and marine sectors have shown interest in the product, and occasional two-speed applications like drilling augers and process conveyors are also considered viable, especially as the compact, modular configuration of planetary gearing can be exploited to build multiple reduction stages and virtually unlimited ratios.

Listed in the current Reggiana Riduttori Series 2000 print and CD-ROM catalogues, the standard RC mechanical gear change is designed to integrate with male and female versions of the RR510 linear reduction gears, nominally rated at 6000Nm output torque, and adds only 85mm in length to the standard box.

With a diameter of just 195mm, the lightweight, compact 1:1 gear change can be combined with any of the standard catalogue gear ratios (1:3.4/4/5/5.8/7), then additional reduction stages fitted to give yet further ratio options.

Maximum input speeds range from 850 to 1750rev/min and engagement is normally carried out when static, although changeovers may be carried out at creep speeds up to 15rpm.

As well as lending themselves to a broad range of stand-alone applications, the RC/RR510 combination can also be used as the primary stage for bigger Series 2000 gear units, with much higher torque capacities, exploiting the fact that the gear change is installed at the low-torque/low-cost end of the drive chain.

Other special RC versions are additionally available to order, for matching gearboxes up to the RR 50000 M/FS models, which are continuously rated at 600kNm.

While a standard gearshift lever is normally used to operate the RC unit manually, it can be alternatively connected to a hydraulic/pneumatic controller or an electric servomotor to facilitate remote operation, thereby expanding its suitability for many industrial and offshore applications.

As there are no ratios built into the gear change itself, specification is relatively straightforward as the ratios are effectively those of the gearbox attached.

Potential applications for a two-speed device include deep sea recovery and cable inspection vehicles, where unladen cable could be wound in far quicker; drilling machines, where a high torque mode could retrieve an embedded auger or a low torque/high speed drive could be used for routine withdrawal and discharge; and industrial conveyors and other plant, where a mechanical speed change offers more flexibility than inverter-controlled motors alone.

As a disconnect mechanism, normally used in conjunction with a fail-to-safe brake to prevent the load running away, the RC also has considerable potential: to disconnect or engage a standby drive in a multiple drive configuration, for example, to disengage a winch and assist 'heave compensation' in deep sea exploration or to enable 'free rise' in hot air balloon recovery operations.

Moreover, the affordable price and simple mechanical design this Series 2000 modular addon enables designers to enjoy the luxury of including 'another gearbox' or a mechanical disconnect, without paying a premium price.