Speed demons

As radio remote controls grow more powerful, with their own feedback screens, for example, users are able to do more with them. Now it is common for remote control screens to show radio signal strength, load on the hook, crane configuration and alarms. They are also allowing users to customise the cranes for the job in hand.

Italian company Imet's new radio remote controls have a digital speed control (DSC) function that can temporarily increase, or decrease, the crane's working speed up to preset maximum limits. Users can increase the speed of every motion of the crane: slewing, first boom, second boom and jib, for example, in a knuckleboom crane.

"When people buy a hydraulic crane, they have different situations of work," says Alessandro Andreon, Imet export sales technical advisor. "The accuracy that they need to manage lifting glass is not the same that they need when managing bricks." He adds later: "In the morning they can adjust the settings to bring bricks; in the afternoon they can adjust the settings to make the movements more accurate."

To make it work, operators flick a switch on certain remote controls, and then press and hold a second switch up to raise the speed, down to lower it. They can check they have it right by operating the crane with the joysticks or paddle levers. Users can adjust the maximum and minimum speed separately. The control works with any analogue outputs for variables such as speed (using PWM or Danfoss-type outputs). It does not work with on/off outputs. The DSC feature requires an Imet L or H remote control receiver.

The settings are saved in RAM, which means they are erased once the unit powers down. When users switch the control off, the new settings disappear and the unit re-sets to original factory conditions.

This design is the best compromise between customisation and standardisation, says Andreon. "When a particular situation is finished, it is better to come back to standard settings, which are okay for many different situations."

In fact technicians who want to make permanent changes to the system can also do so remotely. They enter a PIN code and can enter a special settings mode where they can adjust every speed and try it out with the controllers. Unlike DSC, this feature is not new to Imet.

A similar remote-control adjustment feature that makes permanent changes is now being offered by Spanish control manufacturer Ikusi. A software upgrade in the company's TM 70 remote controls now allows users to adjust speeds to smooth jerky movements and improve speeds.

Users enter a special programme called 'tele-teaching' to set-up all the parameters of the machine's movement. A menu system on the LCD 70 display guides users through the process.

When users are tele-teaching the Ikusi system, what they are actually doing is making (remote) changes to an electronic board that slots into the TM70 receiver. There are two such boards available, one for hydraulic machinery such as knuckleboom cranes (the A21CAN) and one for tower cranes that use PLC-controlled electric motors (the A2VCAN).

Ikusi has already built TM70 systems with tele-adjustment for cranes and aerial work platforms.