Pneumatics lets transport device maneuver parked aircraft by hand.
Moving heavy rolls of paper, railway cars, and even parked aircraft by hand may sound like magic, but it is possible thanks to an unassuming device from Easy Roller GmbH, Feucht, Germany. As its name implies, the Easy Roller lets users easily maneuver up to 100 tons without exerting a great deal of effort.
The keys are a compact pneumatic motor and a mechanical design that takes advantage of a heavy object’s own mass to generate movement.
The heart of the device is a drive roller that sits above two rubber casters which contact the ground. Springs press the front caster against the drive roller, while the rear caster is free to rotate. A chain drive connects the air motor and drive roller.
| The Easy Roller uses a small air motor to move large rolls, vehicles, and railcars. |
Opening a valve starts the air motor, which generates backward rotation in the drive roller. The drive roller, in turn, imparts forward motion to the front caster and the Easy Roller travels toward the object to be moved — say a cable drum. Contact with the drum forces the drive roller downward and against the rear caster, further transferring torque that causes forward rotation. Sufficient pressure of the rubber drive roller against the drum prevents sliding contact, so the drum begins to move. (See more on how it works at tinyurl.com/4nlr83z.)
A small, compact vane motor from Deprag Schulz GmbH in Amberg, Germany, was specifically designed to power the Easy Roller. According to Deprag’s Project Manager Dagmar Dbbelde, the air vane motor has a 1.2 kW (1.6 hp) capacity and nominal torque of 500 N-m (369 lb-ft). The motor is only 218 mm (8.6 in.) long with a diameter of 100 mm (3.9 in.) It weighs only 9.1 kg (20 lb) and has an idle speed of 100 rpm.
Air motor benefits
Why vane air motors for this application? According to Andreas Hufmann, managing director of Easy Roller GmbH, air motors have many advantages over their electric counterparts. Perhaps most important, he says, is the high power density of air motors. Depending on the model, they only have one-fifth of an equivalent electric motor’s net mass and one-third of the overall size. Within certain speed ranges, air motors deliver almost constant power. Thus, they can accommodate a wide range of varying loads, with power controlled merely by throttling the air flow.
Further, air motors cannot be overloaded. They can even be brought to a complete standstill under full load without damage. And as air exhausts and decompresses, its temperature drops and cools the motor, making overheating virtually impossible. Finally, they are quiet, present no electrical hazards, and generate no harmful emissions. (To learn more about air motors and how they operate, click the Fluid Power Basics button at www.hydraulicspneumatics.com.
A variety of Easy Roller models handle different applications. Wheeled-transport versions with driving rollers, as described above, are suited for large rolls in the paper and printing industry. For moving aircraft and heavy vehicles, devices with grooved drive rollers better transfer power. For cars, adding a thrust bar enables forward movement or, when necessary, movement in both directions. The company is also developing a version that functions as a portable conveyor system for in-plant use.