Funicular railway - further help needed

Funicular railway - further help needed

Author
Discussion

oliverhanmer

Original Poster:

42 posts

115 months

Saturday 3rd October 2015
quotequote all
Hi All. So you may remember the long story of getting my funicular railway fixed. Here's the link to the original thread if anyone is interested. http://www.pistonheads.com/gassing/topic.asp?h=14&...

It was a resounding success at the time and we've had a few months of it working. We now have a problem with the funicular and I'm returning therefore to piston heads for advice. The two original PHers who helped so much with it are swamped with work so I'm after a bit more guidance. I posted the text below in the original thread but conscious it's a bit old I thought I'd start a new one.

The motor is the problem. It's a single phase brake motor which has a gearbox attached to drive the cogs that move the chain and therefore the carriage up and down the track. The motor has two capacitors both of which have blown. They were run capacitors with 16uf and 40uf ratings. I've replaced them and it worked for a bit - although it needed a push to get it going if it had any weight in it- but it's now stopped working altogether. The motor hums but just won't start. I've wondered whether I need a start capacitor and a run capacitor rathern than two runs but I'm not sure if that would help or what rating I should get.

I'm increasingly coming to the view that a new motor and gearbox is the best option. It would require a bit of engineering to get the shaft holding the chain cogs attached to the gearbox but I've assumed that's not too tricky - correct me if I'm wrong.... The motor just seems a bit unreliable - you might remember it was the original one that I had rewound - and given that it's what does the leg work I need something I can rely upon. I'm not sure if I need another brake motor - I'm told they are rare in single phase and expensive, or whether I can get away with a standard one and rely on the tension in the chain to hold the carriage in place. It sits quite happily in the middle of the slope without the motor working. I think I would need a motor and gearbox as the current system has a bespoke fitting on the shaft connecting the motor to the inner workings of the gearbox.

A motor seller I spoke to said something about checking the power supply to the motor because if that's dropping when the motor starts it often can cause the humming but not starting symptoms I've mentioned. I've not done that - not sure I know how - but does that sound like that could be the cause of the problem?

A response on the original thread, for which thanks, suggested the starting switch might have gone. Is that an easy fix?

I'd be grateful for any advice/thoughts. Having had it working we (and tescos delivery men) really miss it!

Let me know if you need any more info/pictures etc.

singlecoil

33,307 posts

245 months

Saturday 3rd October 2015
quotequote all
The motor seller means (I think) that the voltage is dropping too much when the motor tries to start (the point at which current draw is at its maximum. You need to get a meter that can read at least 240V on the supply to the motor (at the motor itself) to take account of the length of cable that feeds it. Voltage should be the same as in the house until you switch the motor on.

What I can't tell you is how much voltage drop is acceptable, you would need to consult a motor specialist for that.

eliot

11,361 posts

253 months

Saturday 3rd October 2015
quotequote all
Surely whoever rewound the motor would be the best people to ask for advice regarding the caps.
My limited experience of motor caps suggests a humming motor that turns slower than normal aftet a physical nudge requires a new start cap.

souper

2,433 posts

210 months

Sunday 4th October 2015
quotequote all
Replace electric motor with a 250cc motorbike engine! yea i've had a few...

andrew830

141 posts

206 months

Sunday 4th October 2015
quotequote all
It sounds like who ever rewound the motor didnt do a full rebuild,if it hums its not getting enough startup power which is provided by the start windings.
Its either the start cap is bad the centrifugal switch isnt working or the start windings have gone.
If it was mine i would take the motor off and send it to http://cornwallpumpandmotorrewinds.co.uk/
They have been repairing motors for me for years and are very good.

dave-the-diver

243 posts

185 months

Sunday 4th October 2015
quotequote all
Do be a little careful before removing the brake from the system.

Just because "It sits quite happily in the middle of the slope without the motor working", does not mean it will come to a halt if the motor is switched off when the carriage is in motion down the track.

If the gearbox is a right angled worm style 'box, the static and dynamic friction characteristics will be very different, and a statically self locking gearbox can easily become dynamically reversible.

David

tactical lizard

164 posts

130 months

Sunday 4th October 2015
quotequote all
If you are going to replace it then I would look at a 3 phase motor and a single -> 3 phase inverter to run it.

Then you can have other features like starting speed so it speeds up gradually etc.

hidetheelephants

23,731 posts

192 months

Sunday 4th October 2015
quotequote all
tactical lizard said:
If you are going to replace it then I would look at a 3 phase motor and a single -> 3 phase inverter to run it.

Then you can have other features like starting speed so it speeds up gradually etc.
What he said.

hidetheelephants

23,731 posts

192 months

Sunday 4th October 2015
quotequote all
I can see one potential problem straight off; there's no cooling fan and no cooling fan cowl. If it's been running for long periods like that it may have overheated the motor and damaged the coils. From the other pics it didn't have the cowl before, which may be why the motor was banjoed in the first place.

oliverhanmer

Original Poster:

42 posts

115 months

Sunday 4th October 2015
quotequote all
Thanks for the responses. My sense is that the first thing to do is to establish how 'banjoed' the motor is by getting a company like the one suggested to have a look and to advise on cost. I'd prefer to keep it simple and a converter and new three phase motor, whilst attractive, seems more complicated given that I'm not hugely skilled in this kind of thing.

I can ask the motor company to repair it and add a fan, deal with the capacitor issue etc if it is economical to do so rather than start from scratch with a new motor.

Does that sound a sensible way forward?

Thanks again for all the advice.


hidetheelephants

23,731 posts

192 months

Sunday 4th October 2015
quotequote all
It is a reasonable way of doing it, I'm just concerned that it's gone tits up so quickly after being rewound and repeating the process might just get you back here again in 6 months and the cost of another rewind/whatever down.

hidetheelephants

23,731 posts

192 months

Sunday 4th October 2015
quotequote all
A likely replacement motor/gearbox and a possible replacement motor with a spookily similar helical pinion fitted on the end. both are 3 phase and would need an inverter to power them; 750w inverter drives are available from £80 or so.

BlackZeD

772 posts

207 months

Sunday 4th October 2015
quotequote all
You may also want to check that the motor is big enough and can pull the weight of the lift box FULL easily.
What was originally there before that cart was built?
It may be a weight issue versus the HP of the motor........ more horsepower needed then wink

Get a new 3 phase one specced by the rebuilders above (with some spare power) with an Inverter.
Have a machine shop or the rebuilders make a drive plate, mounting and sprocket to fit.
Then you can set the speed ramp up time, running speed and slow down time and speed etc.

Best option all round in my opinion.

tactical lizard

164 posts

130 months

Sunday 4th October 2015
quotequote all
It sounds like you want to do all this DIY but it might be worth getting a proper spark in to wire up a 3 phase motor and control gear if you go down that route.

The ones that the previous poster linked to are the sort you need, but you would need to make sure they have the correct mounting flange sizes etc.

3 phase isn't witchcraft and if you wanted to do it DIY then there are people on here who can help you,


oliverhanmer

Original Poster:

42 posts

115 months

Sunday 4th October 2015
quotequote all
This is hugely helpful. Thanks everyone. My inclination always is for DIY because I enjoy the challenge but I'm nervous of electrical stuff so I think I'll need expert input.

How do I know what horse power I need for the motor? We made a frame and box and it's fairly heavy. It's hard to know what was there before because it was completely derelict when we moved in. I think though it was much smaller and therefore lighter than what's there now.

If I accept that the current motor is not worth repairing, I'm persuaded by the three phase idea with a converter. I'd definitely need an electrician to sort that out - what kind of electrician do I need? Does anyone know someone near Caterham in Surrey?

I'm not sure whether I buy a new one that is then engineered to fit my gearbox or whether I buy a motor and gearbox. I think the former seems better - the gearbox is in good order. The one linked to on eBay seemed to look right but I'd need to check measurements of connections to the gearbox etc. What else would I need to worry about?

As ever I'd be lost with piston heads so thanks again everyone for all the advice.

hidetheelephants

23,731 posts

192 months

Sunday 4th October 2015
quotequote all
The plated power is more than enough; the set-up should shift the trolley at 0.44m/s and cover the slope in ~67 seconds. With a slope of 1:3 and assuming a gearbox efficiency of 80% 750w is enough to raise 450kg on paper. The trolley probably weighs ~50kg or so call it a safe 250kg.

minivanman

262 posts

189 months

Sunday 4th October 2015
quotequote all
3 phase with inverter is very easy. I worked mine out pretty easily, and I was adding extra layers of complication with a potentiometer for speed control. Any competent spark should be able to do it I'd have thought.

tactical lizard

164 posts

130 months

Sunday 4th October 2015
quotequote all
Don't forget that a motor kw rating is based on 430v 3 phase,

Most single phase inverters put out 230v 3 phase.

So the 0.75kw motor might only actually put out 0.5kw.

Most motors will have a power rating at 230v if you look at the data plate,

You may need a 1kw or slightly bigger motor,

This is piston heads, bigger is better.

You can give us a start by telling us the details of the original motor,

Kw,
Rpm,
Frame size etc

At least then one of us could point you to the correct motor and inverter

oliverhanmer

Original Poster:

42 posts

115 months

Monday 5th October 2015
quotequote all
Thanks for the advice. The plate on the motor has the following information:

50hz
240V
5.1 AMPS
0.75KW
38.12/1 RATIO
IP 54
FIN 37 (then there is an RPM but no number)
BRAKE 240/1/50

In terms of frame size I assume you mean the standard dimensions of the motor so length of the motor, diameter of the flange, diameter of the pinion etc....

they are -

from one end of the shaft to the other - 36cm
motor length - 26cm
flange diameter - 12cm
shaft length from end of motor to end of gearbox pinion - 3cm
diameter of gearbox pinion - 3.5cm

is this what is needed? Let me know if you need anything else

the motor attaches with four bolts and metal rods directly to the gearbox, it is not mounted in any other way

I can send photos if that helps, the link to the other thread in my first message has a photo of the motor and the motor plate.

thanks again.

hidetheelephants

23,731 posts

192 months

Monday 5th October 2015
quotequote all
The size is something of a conundrum, as the plate suggests it's a frame 80 motor but the flange does not look like a standard NEMA or IEC flange[fnarr], it's far too small for the power rating. It all looks very similar in size to the SEW Eurodrive motors I linked to, they are in SEW's compact DT range and their catalogue is coy on the subject of flange size/specification.[snigger]