When you fit a motor mover its weight must be subtracted from the user payload. The Club suggests a couple is likely to take about 150kg of equipment, so if a caravan has a payload allowance of 160kg a motor mover weighing more than 10kg would take you over the limit. The lightest mover currently available weighs about 27kg, which could put the typical couple's actual payload up to nearly 180kg. Other systems may weigh up to 40kg, giving an actual payload of 190kg.
If your caravan has a more usual allowable payload of about 200kg you're okay, even with the heaviest mover fitted, but take extra kit for a couple of children and you could be overloading the caravan. So do check your allowable payload and the weight of the mover. Even if you think you can manage the extra weight, it may be worthwhile visiting a weighbridge after the mover is fitted when the caravan is loaded to check you are within your allowable limit.
Ease of use
There are several ways for the drive rollers to be engaged on to the caravan wheel. Some use a manual over-locking cam device that's quick and you know the roller is fully engaged or disengaged, but requires more effort to put on. Other systems use a screw wind-on action, which is slower and depends on the operator to ensure the roller is fully engaged or disengaged. There's also a more expensive electrically-driven engagement system available. If you have difficulty with hand strength it may be worth trying a manual systems before you buy.
Most manual systems offer a facility referred to as cross-actuation where the rollers on both sides engage simultaneously by operation from just one side. This is more convenient and is essential if you wish to store your caravan alongside a wall, as it's not recommended to keep a roller pressed against the tyre over a long period of time. The downside of operating both rollers from one side is the extra effort required. The fitting of a cross-actuation bar also increases weight.
Electrical roller engagement is a convenient feature and can be essential for someone with mobility difficulties. It's important to find out what facilities are available to manually engage and disengage the rollers in case the battery or engagement motor fails.
All chassis-mounted movers come with a remote control unit like a TV remote control. Some movers come with an alternative cabled connection option for the remote control, which enables the mover to be controlled even when working in areas of high electronic interference.
A well-engineered roller that grips well in both wet and dry conditions is essential. Look for a strong large diameter, wear-resistant roller with a rough surface that provides the maximum of contact with the caravan wheel. Rollers can be of one piece alloy material with teeth like open gears or with a synthetic grit covering. Others are made from steel with milled slots, which are harder and less prone to damage.
Soft start and soft stop are facilities offered by some movers and designed to reduce shock loading to the caravan chassis. With simple on/off motors, even a short burst of power may produce sharp movement, giving shock loading to the chassis and also making delicate manoeuvring tricky. Soft start eliminates this by allowing the unit to move off slowly and gives the operator a very high level of control - very useful in narrow entrances and bringing the hitch head over the towball. Soft start with instant stop offers the best level of control for fine positioning.
Good ground clearance is essential. There's no point having a mover fitted if it hits the first road hump it comes to or falls fouls of a deep pothole.
The method of attachment of mover to caravan chassis varies with different makes and each caravan varies, even if with the same chassis. The wheel size may be different, so a mover supplier may not always be able to predict what ground clearance you'll have.
What the supplier will be able to tell you is the maximum depth the mover will hang below the chassis at the
point of attachment so you will be able to work out how much ground clearance you have left.
There's a caravan industry standard recommending a minimum chassis ground clearance of 150mm, so a motor mover with a ground clearance less than this is not ideal. Caravan chassis manufacturer AL-KO has developed a mover system which will fit on a caravan chassis from 2010 and will not reduce the existing ground clearance. More typical clearance is about 30mm below the chassis at the point of fitting.