The great advantage of mobile column lifts is that they can be set up anywhere on flat hardstanding. And since power cables are a nuisance and trip hazard in a workshop, many brands today have wire-free models. These incorporate battery packs for power and wireless data communications to link together multiple columns and share position and safety information to ensure a safe and level lift, even under conditions of variable loading.
Grouping lifts is a task accomplished by pressing buttons on the control. Once connected, pressing on the up or down button on any controller will actuate all of the linked lifts at the same time, to ensure the vehicle remains level. If one column is way ahead of the others, it will be stopped so the others can catch up. If they go too far out of sync, in the event of uneven loading for example, lifting generally ceases. In emergencies, a mechanical lock will kick in to prevent the column dropping the vehicle.
Exactly how they achieve that varies between brands and even individual models. A number of different technologies have been used.
For example, MAHA’s longstanding RGA mobile column lift uses a radio frequency network for communications, reports MAHA dynamometer and garage equipment specialist Louis Tunmore. He explains that up to eight lifts can be connected in a group, and they remain connected even when the columns are switched to ‘sleep’ for charging. LED lights on every column display indicate whether that unit is part of a group and how many other columns are also in that group.
Flexibility of use is due to different operating modes, such as group and individual column operating modes. This enables quick and easy replacement of wheel and axle suspension components when used in conjunction with heavy-duty axle stands. The system also features microprocessor controls and wireless monitoring of synchronisation, along with a mechanically independent locking device. A simple emergency lowering procedure, in the event of power failure, is included as standard.
The RGA column lift’s wheel forks and carriage are attached to a nut pack mounted on a recirculating ballscrew, which runs the vertical length of the lifter. The column determines its lifting height by monitoring the number of revolutions of the vertical screw to which the wheel grabbing bars are attached.
Elsewhere, the wireless version of Stertil Koni’s ebright mobile column lift connects to others – up to 32, to lift multi-car train carriages – using a mesh network. This technology is said to enable a better and more secure connection by jumping a signal from one column to the next, and across the vehicle too. It also helps to improve connection outdoors, where there are no workshop walls for the signal to bounce around the vehicle.
Users link all of the columns in a desired set with an electronic key fob, of the sort used as a key to a locking cat flap. Each column has its own fob sensor on the control panel. Numerous sets can be used next to each other without any cross-communication or interference. To guarantee the safe use of the columns, the workshop manager can restrict fobs to only those technicians that have been fully trained on the system. Without the fobs, the columns will not function.
When it comes to operation, a full-colour touchscreen on each lift column indicates the number of columns found in a set; only after the user presses the ‘select’ button can he or she operate them, as a set, in pairs or as singles. If one of the columns disconnects, there is an audible warning and an error message. The columns can also be locked off with a pin code if required.
Columns automatically disconnect if they are switched off or moved away from the set. This is an important safety feature, contends field service manager Simon Capewell: “You could have a situation where many columns are on site, and, because they are not cabled, you are swapping columns from one set to another, and columns are going up and down all over the place.”
Stertil Koni’s ebright columns are hydraulically powered, and control motion with valves. A potentiometer mounted on each column measures the height. By contrast, its Earthlift mobile column lift, which features unpowered descent that regenerates energy into the batteries, has a hydraulic pump that is driven and controlled by a stepper motor, whose speed of operation determines positioning. A pressure relief valve set to the capacity of each column opens if an overloaded vehicle is lifted, causing the columns’ lifting speed to reduce, if not stop completely.
A hydraulic leak in a column would prompt an error code, and lock out the lifts from use, he says. In the case of a serious leak, for example a split of a hydraulic hose (which is not common) a check valve in the cylinder would actuate, retaining hydraulic oil in the column. Even such a catastrophic leak in a single column underneath a raised vehicle would not overbalance it, says Capewell, because it could only drop a maximum of 35mm before it hit a mechanical lock.
To ensure all is well, Capewell recommends a six-monthly service of mobile column lifts, which is primarily a service inspection. “What we often find is that workshops are experts at servicing and maintaining trucks and buses but low down on their priority list is looking after their lifting equipment,” he observes.
The company employs 10 mobile engineers across the UK, who also carry out LOLER lifting equipment inspections, which are required by law, as well. The service includes a test of the deep-cycle batteries that it fits, which Capewell admits do require replacement over time.
BOX: MAHA'S LIFT NEWS
A new mobile column lift, the C-RGA, is being introduced by MAHA UK in the coming months. The unit, made in Germany, boasts a new communications protocol – double antenna (LoRa radio modulation), which is said to enable interference-free operation. NFC tag pairing brings simple and secure pairing. New lithium-ion battery technology increases battery life by up to three times, it says. Finally, forklift slots incorporated in the base assist with the movement over longer distances in large workshops.
BOX: MECHANICAL LOWERING
Question: how would you safely lower a raised vehicle when one of the column lifts supporting it is no longer working?
Stertil Koni’s Simon Capewell says: “In that situation, there’s always a way. You might get another column or put it on an axle stand. If the truck has been parked on to the mechanical locks during use, to override it you have to raise it off of the lock and pull the lock back before you can start to come down.”
In the case of its hydraulic column lifts, he offers this advice: “If you’re not on the locks, you can manually lower each column by pulling the lock out and manually releasing the descent valves. Drop the vehicle a few inches, and then go to the next column and work your way around until the vehicle is on the ground. That would be the last resort.”