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Imagine a holiday close to nature, in your own bed, your personal comforts at hand, and the feeling of being free. If you have ever traveled in a camper trailer, you likely never want to travel any other way again. In 2021, the Caravanning Industry Association (CIVD) with its headquarters in Frankfurt, Germany, recorded around 78,000 new travel trailer registrations (excluding motor homes) in Europe alone, globally as many as 670,000 – an increase of 34.6 percent. Traveling with a camper trailer is a major trend.
The Mover enables an independent camper life
To that end, it is no surprise that maneuvering systems are among the most popular retrofit solutions for travel trailers. Truma has given their models the name “Mover”. The Mover is a battery-powered maneuvering system that allows you to move even heavy caravans effortlessly into the tightest spaces with millimeter precision. Drive units mounted on the chassis with specifically developed drive rollers make precise pitching possible. To transmit torque, the drive rollers are pressed against the tires of the trailer. Using the remote control, the maneuvering system can be controlled autonomously from the tow vehicle.
Truma Gerätetechnik GmbH & Co. KG is the clear market leader in the segment of electric maneuvering systems in Central Europe, and with the British sister company, Powrtouch also in England. About 22 years ago, the hidden champion was so successful with the launch of the first Mover that their trademark-protected brand name has now become the generic term for electric maneuvering systems, like “velcro” or “bubble wrap”. Reminiscent of “to google”, “Mover” is now often used as a verb in German-language camping forums, where the arduous pitching “without” is an ongoing theme, especially since parking spots at home can also be challenging.
The extensive Mover portfolio from Truma not only comprises a substantial amount of development work and experience, but also powerful and robust components. For this reason, Truma relies on the drive systems and drive rollers from Parvalux Electric Motors Ltd., located in Bournemouth, UK, for their models Mover smart A and Mover smart M. Parvalux specializes in small motors and angular gearheads with high reliability and has been developing and manufacturing brushed DC motors, AC motors, and gearheads for more than 75 years, for industrial automation systems. Since 2018, Parvalux has been part of the maxon Group and complements their expertise for smaller, more precise units. Truma and Parvalux have a long-standing relationship – their collaboration dates back 20 years. “Once a week, our teams exchange information, views, experience, and ideas about various topics and projects,” explains Andreas Schmoll, Senior Product Manager Caravan Mover at Truma. “This is also an important contributing factor regarding the reliability of the devices.”
DC motors provide uniform power output
Parvalux designed the gear motor along with the drive rollers for the Truma Mover smart A and Mover smart M to accommodate extreme strain. It consists of the brushed motor PM 63, a permanent magnet DC (PMDC) motor that Parvalux has adjusted and fitted with a suppressor for the application. The advantage of PMDC motors is not only their flexible design, but they also provide a uniform power output. This is important in bends and on inclines. Another benefit: Like most loads in RVs that are supplied by the battery of the caravan, the motor of the Mover runs on 12 V DC.
The gearhead from Parvalux is an angular gearhead of the self-locking type M10SX. The screw drive transmits the power only in one direction. In case of a voltage drop, this ensures that “the travel trailer does not carry on moving on its own.” The aluminum drive rollers with wave profile and specifically roughened surface are custom-built. The steel construction, covering, control unit, remote control, and software are all produced by Truma.
Generally, electric maneuvering systems differ in terms of the mechanics that slide the rollers onto the tires. For semi-automatic systems, the gear motors with rollers are manually pressed against the tires using a lever. With automatic systems, only the push of a button is required to activate a separate motor for carrying out this task.
Otherwise, the device concept of both models is essentially the same: next to each of the two trailer wheels, a drive system with an integrated drive roller is clamped to the chassis using Truma’s patented quick fastening system. For the Mover smart M, it also includes a lever for sliding the roller onto the tire. For the Mover smart A, an additional motor from Parvalux is integrated on each side to carry out this task. A multi-part steel tube connects the left and right side mechanically. The motors are connected to the control, located inside the travel trailer, via cable harnesses, which were designed to accommodate high currents. In turn, the control is connected to the on-board battery. When maneuvering the trailer uphill on a steep incline, currents of up to 120 A may flow.
Proper grip is key
The application is faced with the challenges of pressing the rollers onto the tires with enough force as well as the maneuvering task itself. “With both variants, an incredibly strong force is applied to the rollers when pressed against the tires to ensure ample grip. About 4,500 newtons act on the tire, or rather 450 kg are pressed into the tire,” Dr. Andreas Schmoll explains one of the engineering requirements.
The grip of the roller on the tire is also very important, as the driving torque is transmitted via the roller. Additionally, Parvalux gave the surfaces of the aluminum rollers a very rough structure. “This further improves the transmission of power to the tires.” A great amount of know-how and development work has been invested in these devices. It was an engineering feat to ensure that the rollers do not damage the tires under any circumstances while engaged.
Other requirements for the application arise from bumpy terrain or obstacles. “If the right-side drives over a curb and becomes slower as a result of the higher strain on that one side, the Mover’s performance must not drop sharply,” says Dr. Schmoll. Consequently, the entire system had to be designed to accommodate asymmetrical strain. For this reason, Truma designed the devices with reserve capacity.
Another essential feature is the self-locking M10SX gearhead from Parvalux. The screw drive transmits the power only in one direction. “This is a crucial safety requirement. If a voltage drop occurs for any reason, e.g., because the remote control has been dropped, the gearhead has to self-lock. In practical terms, this means that the gearhead must be able to bring the weight of two metric tons to a complete standstill, even on a hillside,” says Dr. Schmoll.
When it comes to maneuvering using the Mover, speed is counterproductive anyway. Pitching is about precision. The Truma Mover can drive forward and backward, straight ahead, around a bend, and rotate on the spot. Therefore you can maneuver your travel trailer at ten meters per minute onto any pitch with millimeter precision. All of this effortlessly via remote control, and if you like, even from the comfort of your camping chair.
