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Looking for rollers to add to a trolley


Stuart91
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One of our lockdown projects was building trolleys for staging decks. They look not unlike this.

 

The biggest trollies are holding 8ft decks, but even the 2m models are a bit on the long side, and with a castor on each corner, the middle section "grounds" when going up a ramp into a vehicle. The obvious answer is to add another set of castors in the centre, which is what we've done.

 

The problem now is that one end of the trolley sticks way up in the air whilst it balances on the other four castors. You end up reaching an awkward tipping point when the middle castors reach the top of the ramp, then it comes back down with a worrying thump. This makes the operation quite hard to control, and castors can also swivel unhelpfully and either snag the edges of the ramp or try to escape entirely.

 

What I'm thinking of is some kind of low-profile roller that we could attach in place of the centre castors. The challenging bit is the weight, the trolleys can be up to 270kg when fully loaded. And I'm ideally looking for something around 40mm total height if we're to gain much against the castors.

 

I'm struggling to find anything suitable. The last rollers I bought were for the back end of a trailer (to stop it grounding) and these were quite large and expensive, and came in as a special order from an RV dealership in the USA. I'm sure something smaller will exist, but most of the rollers I can find are designed for much lower loads.

 

5-Star cases are my usual option for more specialised hardware, but they haven't been able to come back with anything. I can't imagine that I'm the only person with this problem, so hopefully there's something out there that I'm missing. Or is there a better solution to the problem that I've overlooked?

Edited by Stuart91
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How about a PTFE skid plate along the outer rails either side rather than castors in the middle?

 

Good idea! (And stirring vague memories of "tail bones" on skateboard decks from the days of my youth)

 

How long is PTFE likely to last?

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How long is PTFE likely to last?

 

How long's a bit of string? How heavy is the trolley, how often is it being loaded into vans, how rough a surface is the PTFE being dragged over, what grade is the PTFE, etc.

 

It's pretty hardwearing stuff, but can split/tear with impact forces or gouging surfaces.

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https://www.varley-c...els-and-Rollers

 

what about pallet truck wheels? they take massive loads and if the roller was slightly less tall than the castors it would remain out of the way on flat ground.

Not too hard to make a steel U bracket as a mount, and the roller would only come into play when the front wheels lift off.

 

Or if it's your truck that's always used could you use machine skates? so the rollers face upwards and the trolley bears on the skate and rolls along?

 

either way it's going to move quickly when it reaches the balance point unless some damper (human or mechanical ) controls the speed of the see-saw

 

I have a feeling it would be easier to buy a new arched ramp that works for your trolley length- the angle of front to centre of trolley can be halved.

Edited by Dave m
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Would it work to replace the middle casters with fixed swivelling wheels that can't swivel?

 

That would fix the swivelling problem, but not the issue with the other end rising too far.

 

I've recently bought a longer ramp, which helped things a little but the problem is still there.

 

Is more ground clearance not an option? We used rolling riser legs in this sort of dual purpose role.

 

That's a good piece of lateral thinking, but I don't think it would work in this scenario. One problem is where the trolleys are stored - underneath a mezzanine that was custom built to suit their height! Also I'd be a bit worried about centre of gravity etc. when moving them around.

 

Our trolleys have the decks sitting vertical. If we put wheels into the bottom deck and moved piles around, it won't fit through doors or on any of our van ramps. It's a fine solution for larger operations than ours.

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Would it work to replace the middle casters with fixed swivelling wheels that can't swivel?

 

That would fix the swivelling problem, but not the issue with the other end rising too far.

 

I was thinking that if the centre wheels couldn't swivel it would at least make the "tipping point" more manageable, but sure, it's not ideal.

 

 

 

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what about pallet truck wheels?

 

There's some interesting possibilities there. I hadn't thought of pallet trucks as a possible source.

 

Or if it's your truck that's always used could you use machine skates? so the rollers face upwards and the trolley bears on the skate and rolls along?

 

Unfortunately we use a mix of vehicles. It might be interesting, however, to modify a ramp instead of the vehicle itself.

 

I have a feeling it would be easier to buy a new arched ramp that works for your trolley length- the angle of front to centre of trolley can be halved.

 

Certainly adding a longer ramp has helped the process. (Going to 240cm from 180cm doesn't sound like a lot, but it does make a difference)

The profile of the top lip isn't ideal, it's an angle rather than a curve so there's a distinct edge which is where things catch. I'll certainly keep an eye out for anything more suitable.

 

(That edge is part of the reason I'm worried about the longevity of PTFE, we'd essentially be running it over a sharpish edge with 100+kg bearing down on it)

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You have found out why piano movers use dollies! I don't see how adding anything to the design for an 8ft load will make it more manageable without a tail lift - or a ramp of pretty well infinite length. Adding a set of central wheels has only given you real problems by adding a very efficient fulcrum for the over a quarter of a tonne load. This simply can't be risk assessed as safe in my opinion. As Kerry says you really need more ground clearance. Actually you really need a better idea - I wouldn't go near something homemade like this of 8ft length with that load on it frankly. Laid flat on a decent dolly - the job would be a breeze.
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What about the sort of rollers that you would find on boat trailers? I can't find a picture to hand, but IIRC, my trailer has got a pretty much full-width rolling steel bar on the back of it that the launching trolley rolls over.

 

Edited to add:http://www.irwdesign.com/br/trailer2.jpg

http://www.irwdesign.com/br/trailer.JPG

 

Edited by IRW
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I sympathise with narrow doors and corridors but we used to store steel deck flat, bottom one on wheels.However in your case it sounds as if you'd still have the see saw effect due to a short or too steep ramp.I suppose a tail lift is out of the question? Or a dock lift?

Using a longer ramp with a curve helps and maybe a winch to control the in/out movement? Plus more people loading?

I'd be concerned that it might fall to one side and flatten someone who tries to keep it upright as well.Maybe having the pivot wheels just off centre, towards the front(?) would slow down the crash to the truck floor?

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Are your current 4 wheels in the corners of the trolley? Moving the existing wheels inwards to create a shorter wheelbase with greater overhang at each end could help, much like when putting 3m truss on dollies there is a sweet spot where they don't scrape on ramps. The caveat is go too far and the overhangs can dig in...
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So As Isee it, the issue is with 4 casters on the vehicle and 2 in the air above the ramp the middle caster suddenly falls of the edge.

 

How about fitting 4 extra casters just each side of balance point but not so close they jam on each other, get to the point of only 4 casters on the van and the trolly will start tipping and then the whole weight will be taken on the other 4 on the ramp.

 

Or is this what you are aiming for with the rollers?

Edited by sunray
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