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thebriars

Better Motor Movers

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Motor movers have been around for quite some time now, and many caravans have them fitted. Isn't it about time that the caravan chassis makers designed an inbuilt system that, say, used gears directly onto the hub instead of the very crude system we have today?

 

I know Al-ko did provide one that bolted straight onto the chassis at a hopelessly expensive cost, but it still relied on a friction drive onto the tyre.

 

Or is this just another example of just how out of date the whole caravan industry is?

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To provide the kind of thing you are proposing would require a much more sophisticated piece of engineering than we have at the moment and that would be much more costly to produce than our current system.

 

John. :)

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Not necessarily. A great part of the mechanics of our current system is because its an after market bolt on system. For example, a simple self-engage clutch system akin to a starter motor could replace the mechanics required to wind the motors onto the wheel. Gearing could mean smaller cheaper motors, especially if using digital outrunner motors which are far more efficient than brushed motors.

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Motor movers have been around for quite some time now, and many caravans have fitted them. Isn't it about time that the caravan chassis makers designed an inbuilt system that, say, used gears directly onto the hub instead of the very crude system we have today?

 

I know Alko did provide one that bolted straight onto the chassis at a hopelessly expensive cost, but it still relied on a friction drive onto the tyre.

 

Or is this just another example of just how out of date the whole caravan industry is?

No not at all in this case IMO.

 

Any gearing would need to be clutched in some way and in such a hostile brake dust infused environment would need a sealed enclosure and be lubricated for life. Then there is getting a location for the motor and a drive system in. Plus, this would increase the unsprung mass with all thats ramifications.

Here using well proven widely used motor units and simple gearing plus a crude but effective friction drive is all the complication and sophistication we need and comes at a reasonably affordable price.

 

In engineering, it is the easiest thing in the world to complicate things over much, the brilliance is designing simple; that we have if rather rudimentary.

I would like to see more following the Mammut concept and an acceptance by Al-Ko to design for the fitment of movers generally, as underslinging and clamping onto the girder return fold is not best practice.

 

Edit: the starter motor concept of clutching would not address the unsprung mass and I like a soft start to my mover not rocket away as if trying to fling an engine crankshaft round to start the thing.

Edited by JTQ
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A number of modern cars have simple rear hubs which can be driven or non-driven as required - primarily those fwd cars that have a 4wd option - the driveshafts are bolted to the back of the hubs and transmit the drive from the rear diff, or in some vehicles the two rear electric motors.

 

A similar design could be adopted for caravans as the drive shaft could be fairly small diameter given the low torque involved - but it would require a redesign of the chassis and limited to caravans, as few other trailer types need a mover.

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There already is a system where a motor drives the wheels without using a friction roller. It is fitted to vehicles we call motorhomes :blush:

As a caravan is essentially little more than a trailer, the current system is probably the best we can expect at an acceptable price. With thought it should be possible to fit a small electric motor directly to the rear of the brake hub assembly but I suspect that would not be at a price acceptable to caravanners as we hear moans already about the cost of the basic friction roller drives.

I accept that they have their use but in my opinion movers are really only for occasional when the caravan cannot realistically be moved using the towing vehicle.

Rallier.

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If you think of the current system used on motor movers. On boggy ground the tyres don't need to have traction with the ground to move the van, they work like you have your hand on the tyre and roll it out. Where as if you have something geared to the hubs, then it would have a similar effect as a car stuck in mud the tyres would skid.

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Not everyone wants motor movers. ...several of the models we recently looked at,as 2 and 3 year olds,had never ever had them and their new owners were not specifying movers for their new 'vans.

 

geoff

Edited by shipbroker

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Edit: the starter motor concept of clutching would not address the unsprung mass and I like a soft start to my mover not rocket away as if trying to fling an engine crankshaft round to start the thing.

As I said a smaller digital motor would greatly reduce the unsprung mass, and with a digital motor, you can easily have soft start if so wished, and variable speed too.

If you think of the current system used on motor movers. On boggy ground the tyres don't need to have traction with the ground to move the van, they work like you have your hand on the tyre and roll it out. Where as if you have something geared to the hubs, then it would have a similar effect as a car stuck in mud the tyres would skid.

 

Noooo! There would be absolutely no difference between a hub driven mover and a friction wheel driven mover in this respect. The friction between the mud and the tyre has absolutely no notion of what is turning the tyre.

 

However, in the above case, mud on the tyre will reduce the friction between the tyre and the mover roller, inducing slip there.

Not everyone wants motor movers. ...several of the models we recently looked at,as 2 and 3 year olds,had never ever had them and their new owners were not specifying movers for their new 'vans.

 

geoff

 

Does it have to be fitted? I'm sure a system could be devised very cheaply where one had the option to fit from new or as an after-market fit.

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If you think of the current system used on motor movers. On boggy ground the tyres don't need to have traction with the ground to move the van, they work like you have your hand on the tyre and roll it out. Where as if you have something geared to the hubs, then it would have a similar effect as a car stuck in mud the tyres would skid.

If the tyre does not have traction with the ground, the van won't move! Regardless of how the wheel is driven, whether by gear to the hub or a roller on the tyre, if it's on slippery ground you will get a loss of traction.

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Motor movers have been around for quite some time now, and many caravans have them fitted. Isn't it about time that the caravan chassis makers designed an inbuilt system that, say, used gears directly onto the hub instead of the very crude system we have today?

 

I know Al-ko did provide one that bolted straight onto the chassis at a hopelessly expensive cost, but it still relied on a friction drive onto the tyre.

 

Or is this just another example of just how out of date the whole caravan industry is?

And still do - it is called the Mammut. I had one of these fitted to my caravan pre-delivery in March 2012.

Benefits - fitted so that it is not below the lower surface of the chassis frame, so much less likely to get knocked by high kerbs and verges.

Downside - One side of ours packed in at just over 4 years. No serviceable parts inside, and all the electronics encased in the motors. . Still under parts-only warranty, but would have to take it to the supplying dealer, who would remove it and send it to Al-ko for a decision - not allowed to remove it myself and send it direct.

This would have meant taking it away from the dealer and having to get help to get it back into our very tight 'at-home' storage, with risk of scraping the side windows on the high gates/posts. And then get it out again when (if?) a change under warranty was given (parts only, of course). Also, a planned holiday would go by the board.

 

So I ordered a new Powrtouch Ev (as I did my two previous Powrtouch movers)olution (manual op), and received it today. I am now going to fit it myself (as I did my two previous Powrtouch movers). It's going to take me a little longer this time, as I am now 81! :blush:

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On the subject of possibly having direct drive mover motors, by means of gears directly onto the hub. I suppose the technology is there for this to be possible, but the cost would be enormous. The motors would have to be capable of 'freewheeling' whilst towing, and some form of clutch mechanism to engage them when they were needed to move the van.

The whole axle assembly would have to be redesigned, and the chassis manufacturer would have to be ready to provide different axles - one for those who wanted this mover, and another for the majority of buyers who would not be able/prepared to incur such a high cost. Heaven knows how much a twin axle would cost - double the price of the van, maybe?

 

Somewhere along the line a feasibility study may have been carried out, but the economics would certainly kick it into touch!

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Why should a twin axle cost double, surely just a more powerful motor on a single axle?

 

Funny how dismissive and negative everybody is without really considering the idea. Talk about cup half empty!

 

No, can't do it it would cost too much. Come on the present generation motor movers cost around £800+ for cheap motors, a crude control box (they are seriously crude electronics), a very simple remote, and lots of heavy bolt on metalwork. Just as a comparison, a very simple comparison, a pair of remote controlled gate openers, £350! We're already being fleeced! A digital motor giving 3kw of power is just 50mm diameter and costs under £60 retail. An electronic controller with all sorts of sophistication including slow start etc costs about £30. The only other electronics needed is a remove and a receiver in the van, bringing the total to about £220. Not expensive.

 

Too complex, new technology etc. As someone has already pointed out, we have all those mechanisms in electric cars.

 

Perhaps that's why we accept ***** caravans built to pre-war standards and methods. If as caravanners, we accept cr@@, we will get cr@@. If we are happy to pay well over the odds for junk, they will continue to provide overpriced junk.

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The Briars

 

You are the one with the grand idea go ahead and design it! new design and innovation comes from the bold and innovative.

even if I and others can't get our heads around your concept.

Andrew

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I tend to agree with the OP.

We managed to put a man on the moon over 50 years ago and a colour TV in every house (and caravan), but can't improve on the heavy Heath Robinson contraptions we all use now?

 

As for the comment that the wheels would slip, post #9 is totally correct. A 4WD vehicle that has very good slip resistance still drives through the axle.

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Why should a twin axle cost double, surely just a more powerful motor on a single axle?

 

Funny how dismissive and negative everybody is without really considering the idea. Talk about cup half empty!

 

No, can't do it it would cost too much. Come on the present generation motor movers cost around £800+ for cheap motors, a crude control box (they are seriously crude electronics), a very simple remote, and lots of heavy bolt on metalwork. Just as a comparison, a very simple comparison, a pair of remote controlled gate openers, £350! We're already being fleeced! A digital motor giving 3kw of power is just 50mm diameter and costs under £60 retail. An electronic controller with all sorts of sophistication including slow start etc costs about £30. The only other electronics needed is a remove and a receiver in the van, bringing the total to about £220. Not expensive.

 

Too complex, new technology etc. As someone has already pointed out, we have all those mechanisms in electric cars.

 

Perhaps that's why we accept ****** caravans built to pre-war standards and methods. If as caravanners, we accept cr@@, we will get cr@@. If we are happy to pay well over the odds for junk, they will continue to provide overpriced junk.

This is over-simplification at its worst. There would be development costs, the design requiring to meet fail-safe criteria, and patenting costs. As a retired development engineer I can tell you that the costs would be eye-watering before a single unit reached production viability.

Then there is the problem of selling to the public - such a unit could not be automatically included in the assembly, because not every buyer would pay for it, and many of those purchasing a mover would opt for existing proven and much cheaper movers already on the market. So the chassis manufacturer would be compelled to offer an alternative axle assembly.

Dealer service departments would need to be highly trained to tackle caravans with this proposed unit, both in annual servicing and unit failure. Bear in mind that part of the gearbox would be in permanent drive with the road wheels, so regular servicing would be critical. Also, if the permanent parts of the drive seized, the caravan could well easily go out of control - this pre4sents serious risks of liability at law.

Unless the units had clutches to the road wheels, which means more expense and significant additional weight.

 

Apart from Al-ko bolting their mover directly onto the chassis side members, all of the competition still opt for the underslung design - they might modify to use the Al-ko bolt holes once the patents have expired.

It is possible that at least one of the mover manufacturers has explored the possibility of direct-wheel-drive. One has only to consider the above challenges, of which there are likely to be more to add, to understand why the design has not advanced.

 

Don't confuse moving a caravan with opening a gate. The caravan will be much heavier, some terrains will demand a great deal of power to the wheels, and caravan movers have to have electronics capable of precise steering.

The current single axle Al-ko Mammut costs in the region of £1,500 + fitting. And at four-and-a-half years old I have ditched it in favour of a Powrtouch. I can also vouch for the Powrtouch's quality of build, which is quite obvious to anyone with an extensive engineering background.

 

Regarding the need for four motors on twin axles, as opposed to two motors, the reason for this is that, during turning manoeuvres, both outer wheels of the turn have to be driven. With only two motors (as for a single axle) the non-driven wheels would drag sideways during a turn, imposing extra loading on the mover.

In France last year, we had a twin axle with only two motors on the next pitch to us. To enable the van to turn, whilst operating the remote control with one hand, the fellow and his wife had to heave on the rear handles of the van to force it to turn.

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Speaking as a retired design/production engineer myself, while there obviously will be development costs, the problems are far from insurmountable, and all the technology is known. Over-simplification? Not at all, as an engineer I'd have thought a few sums would have answered your concerns. All that is required is an open mind.

 

I do not subscribe to the thought that these would be much dearer. Obviously there will be development costs, on top of production costs, but the picture you are painting is one of complete design stalemate in engineering. I wonder how any new concepts ever come to fruition?

 

As for power, the average motor mover uses around 20 amps at 12v. That's 240 watts of power, or 120 watts per wheel. Even doubling that for a twin axle would give a mover total of 480 watts. Now consider using brushless motors, which are far more efficient, and a total of 500 watts of high torque power geared down would give ample performance.

 

I fly model aeroplanes with electric power, and a 600 watt motor costs less than £20 weighs in at 120grams and will fit in a box about 4cm square. With no moving parts other than the ball bearings there is little to go wrong or wear out, and I would imagine one of my motors gets far more use than a motor mover motor does. Imagine one in each wheel! That would be 5 times the power of today's movers. A motor speed controller is smaller than a matchbox and costs around £20 and would give precise control forwards and backwards at an infinite variety of speeds. Fancy having a reasonable variable speed instead of the frustratingly slow crawl currently available?

 

Apart from the motor efficiency, extra efficiency would be gained from a direct drive as opposed to the crude friction drive of current systems.

 

Controlling the mover? Use either a dedicated mover or a smartphone on bluetooth, the latter with an obvious cost saving.

 

 

Now this thorny, so called, very difficult problem of a clutch etc. Consider the humble car starter motor which has been around for donkeys years. A very simple mechanism engages and disengages the motor and has been used in millions of cars, and trucks over the last 80+years. These days they rarely give problems, and in use they will engage/disengage hundreds of times more than a motor mover. Why invent problems when simple solutions already exist? I bet years ago there were people bemoaning the demise of the starting handle and making exactly the same comments about the new-fangled electric starters!

 

To sum up:

1. The component cost is minimal, almost to the point that they could become a standard item.

2. Uses mostly existing technology.

3. Weight is minimal, just a few kg compared to the 25-30kg of today's systems.

4. No external motors to get damaged on speed bumps etc.

5. A more efficient, effective system

 

It is sad to see so many with negative closed minds. It was exactly this sort of thinking that determined the demise of the UK motorcycle industry and car industry. All our mass manufacture car plants now rely of R&D from other parts of the world.

Edited by thebriars

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The overriding problem is that all caravan owners do not subscribe to a mover, and many who have them can be seen regularly still using the tow car for manoeuvring the van on site, and probably at home/in storage. My own Mammut, now rejected cost twice as much (fitted) as my new Powrtouch has with DIY fitting. And, as I have said, because all owners will not buy a mover, or will go for the current types on offer, the chassis manufacturers would have to provide a choice of axle.

With all this uncertainty would you, if you were a caravan manufacturer, go down this "new technology" road?

With clutches and gearboxes build into the chassis, such a van might easily become deemed a self-propelled vehicle, and attract a road tax. It is not as straightforward as you would like to imagine.

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The 2 Tops

 

"So I ordered a new Powrtouch Evo (as I did my two previous Powrtouch movers)evolution (manual op), and received it today. I am now going to fit it myself (as I did my two previous Powrtouch movers). It's going to take me a little longer this time, as I am now 81! :blush:"

 

Why at your age, with respect, don't you have them fit it.

Quote Powrtouch (in part) " NB. Our guarantee covers reasonable use of the mover, it does NOT cover damage caused by misuse. The guarantee cannot cover any malfunction caused by the fitting of the mover if the fitting has been done on a DIY basis or purchased from/fitted by a non-approved dealer or agent"

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The 2 Tops

 

"So I ordered a new Powrtouch Evo (as I did my two previous Powrtouch movers)evolution (manual op), and received it today. I am now going to fit it myself (as I did my two previous Powrtouch movers). It's going to take me a little longer this time, as I am now 81! :blush:"

 

Why at your age, with respect, don't you have them fit it.

Quote Powrtouch (in part) " NB. Our guarantee covers reasonable use of the mover, it does NOT cover damage caused by misuse. The guarantee cannot cover any malfunction caused by the fitting of the mover if the fitting has been done on a DIY basis or purchased from/fitted by a non-approved dealer or agent"

First point: Having spent my whole life in the engineering industry, I am still quite capable of this work, which has now been satisfactorily completed. Not being limited for time, I was able to carry out a high quality job which is prevented in the allowed time for a 'specialist' to do the work. The "trained dealership engineer" who did the work on the Mammut which I have thrown out, and which was a "dog's dinner" is testament to that.

 

Second point: Any malfunction of the mover due to a fault is covered by the guarantee where the work is DIY, always providing of course that the fitting was correctly performed and the unit has not been abused.

For example: I do the wiring to the battery slightly different than the instruction manual, so that I only have one pair of leads into the battery locker (very little space due to 110 a/H battery). I contacted Powrwheel Tech dept about this, and their manager assured me that this would in no way compromise the warranty.

 

Under the van, the entire cabling is enclosed in 15mm flexible PVC electrical conduit - a fitter would simply not have the time to do this.

Somewhere, there is a 2006 Coachman going around where I provided the same under-van protection for the mover wiring.

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Well done The 2 Tops

I refitted our mover because it too had been put on like a "dogs dinner"!

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Well done The 2 Tops

I refitted our mover because it too had been put on like a "dogs dinner"!

Seems I'm not the only one who can't stand poorly carried out work. I may be my own worst enemy in some respects. I served my apprenticeship working in radar, and everything was subject to AID checks - every soldered joint checked and painted with an iodine coloured solution to indicate it had been inspected, and every nut and bolt, unless subject to a paint finish, was painted with a kind of varnish to protect against corrosion from scratching of the cadmium or zinc plate. They do say that what we learn in our formative years affects our attitudes for the rest of our lives.

And I'm not quite done yet. Over winter I will be tidying up some of the caravan wiring, including the primary 20 amp fuse for the 12-volt system, which at present dangles at the end of loose cables. This will be mounted in a proper fuse carrier, and in a sensible and accessible position. It does seem daft, considering that the PSU fuses and circuit breakers, along with the road light fuses, are all located in purpose made fuse boards.

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