andygtt
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| posted on 13/10/05 at 08:54 PM |
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Electric reverse
Anyone done one of these and have pics etc......
Thinking it would be usefull to at least see how its been done and get views on how effective they really are.
For a number of reasons I'm definatelly not going for a reverse box (cost etc.).
Andy
please redefine your limits.
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mark chandler
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| posted on 13/10/05 at 10:22 PM |
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I have seen a few pictures of this, the ones that they use for racing are based upon motorbike starter motors.
Source the motor and ring gear (spag clutch assembly) from Ebay for £20.
Sandwich the ring gear cog between the Diff flange and propshaft, then devise something that allows the starter motor to engage the gear when required
(cable pull and pivot the back of the starter, solid axle stick it at the drivers end or even in the middle of a two part prop).
This is great as minimal additional mass to the rotating parts and a lightwieght cheap motor that will use a bike battery as a power source... Maybe
limited power but then how often will you use it ?
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Rorty
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| posted on 14/10/05 at 05:58 AM |
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You could use a chainsaw head and run the pull cord through a couple of quality sheaves (light weight yaght types) and have the T handle sticking out
of the dash. 
Chainsaws have a centrifugal clutch, so the sprocket could be left permanently engaged.
They'd also have more power than a starter motor and probably wouldn't weigh any more than a starter plus engagment paraphenalia. 
Who wants to be the guinea pig?
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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RallyHarry
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| posted on 14/10/05 at 08:45 AM |
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How many Nm or ft/lb are needed to reverse a BEC slightly uphill ?
Would a couple of 18v cordless drills do it ?
Cheers
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mark chandler
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| posted on 14/10/05 at 08:58 AM |
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If you want to keep the gears in mesh then the bikes Spag clutch (dunno why they call then this) is a ratchet type affair so one way, cetrifugal
clutches exist on mopeds, quads and lawn mowers.
Moving the gears out of mesh saves weight, mtce and noise. maybe make something based upon a car starter motor, its producing a small ring gear thats
the problem. I compared the gears on a rover V8 cam gear to a Rover V8 starter, not a bad fit and made of steel. So if anyones looking at making
something like this maybe thats an option.
Regards Mark
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Bob C
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| posted on 14/10/05 at 09:14 AM |
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I've said it before - motor bike starter ratchet does the wrong thing for a reverse - it would be OK for an electric FORWARD gear.......
Also any pre-engagement starter motor solenoid does the gear engagement thing for you. It also houses a dirty great contacter which can be used to
power up the reverse power controller - just undo the nut on the solenoid & insert the controller in series.
Bob
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Rorty
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| posted on 15/10/05 at 03:08 AM |
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quote:
Originally posted by Bob C
It also houses a dirty great contacter which can be used to power up the reverse power controller - just undo the nut on the solenoid & insert the
controller in series.
Bob
Can you explain this bit further please Bob?....begining with "take your screwdriver out of your toolbox"....
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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Bob C
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| posted on 15/10/05 at 08:48 AM |
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I'm away on the road this weekend, I'll post something when I get back.
cheers
Bob
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Peteff
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| posted on 15/10/05 at 11:57 AM |
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the bikes Spag clutch (dunno why they call then this) is a ratchet type affair
They don't, it's called a sprag clutch. Should have gone to Specsavers.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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gazza285
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| posted on 15/10/05 at 04:05 PM |
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It's not a ratchet type affair either.
DO NOT PUT ON KNOB OR BOLLOCKS!
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tks
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| posted on 15/10/05 at 05:09 PM |
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mhhh
I was thinking of lasering an 1,5mm sheet
wich fit on the diff and on that welding anteethed ring gear.
then i wanted to use the clutch part of an starter motor.... and use an wiper motor
(maybe from a transit or something..)
to do the movement...
Tks
The above comments are always meant to be from the above persons perspective.
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Bob C
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| posted on 17/10/05 at 09:24 PM |
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Hi rorty, here's a diabolical picture of a starter motor showing where I'm saying break the circuit to put the reverse PWM controller. It
means the controller is only powered when reverse is selected (which can easily be interlocked via the neutral switch) to make it very difficult for
things to go badly wrong!
Bob
 
Rescued attachment starter.GIF
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Rorty
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| posted on 18/10/05 at 06:55 AM |
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Thanks Bob. I'm not an electrical genius, so bear with me.
I've used a started before and just hooked the wires up to a 30a switch.
Obviously what you're describing is more sophisticated in that it makes use of a PWM controller between the solenoid and the bike's
neutral switch. Correct?
I've probably been in danger of starting a fire in the past then.
BTW, what's a PWM controller? 
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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smart51
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| posted on 18/10/05 at 07:27 AM |
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PWM = pulse width modulation. It is a means of varying the voltage by switching it on and off at high speed. The length of time that each pulse is on
(the pulse with) compared to the lenght of time between pulses is what determines the average voltage. It gives you a means of speed control.
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Bob C
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| posted on 18/10/05 at 10:05 AM |
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Hi Rorty,
no the PWM controller is the motor power controller (for less violent reversing manouevres) and it's in the high current path between the
solenoid and the actual motor itself (I promise I'll publish a design for one of these eventually....) The thin wire that goes to the starter
switch is the one that's interlocked with the neutral switch, that way you can only shove it into gear when the main box is in neutral.
Bob
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jambojeef
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| posted on 18/10/05 at 04:42 PM |
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Hello,
Any suggestions for a PWM circuit which would control the current for such a motor anyone?
When I was thinking about this I was thinking that you could pilfer something out of an electric wheelchair (obvously one which doesnt belong to a
diabled person) these have the benefit of some kind of "soft start" too
Geoff
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The Shootist
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 posted on 18/10/05 at 06:15 PM |
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Call 4QD
For under 100 UKP 4QD makes a PRO-Scoota-120 controlled that will put out 115 amp for 1 minute without an extra heatsink.
For a few Quid more you could have a controller with internal reversing in-case you need an "Impulse Speed" to manuever, rather than
playing with your clutch.
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Rorty
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| posted on 19/10/05 at 05:45 AM |
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quote:
Originally posted by Bob C
Hi Rorty,
no the PWM controller is the motor power controller (for less violent reversing manouevres) and it's in the high current path between the
solenoid and the actual motor itself (I promise I'll publish a design for one of these eventually....) The thin wire that goes to the starter
switch is the one that's interlocked with the neutral switch, that way you can only shove it into gear when the main box is in neutral.
Bob
Thanks for your time and patience Bob. I now understand the whys and wherefors.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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uklee70
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| posted on 19/10/05 at 10:34 AM |
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Hi
The great electric reverse debate
I have had the idea for a while of using an
electro magnetic clutch !
this means there is no contact between the two serfaces until an electric currant is passed through the clutch
as my car is mid engined I was going to mount this on the front sprocket and use a winch motor
As this is just an idea and my engineering skill is not great
I this a good idea or am I just a complete fool
Be gentle with the reply's
regards Lee
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MikeR
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| posted on 19/10/05 at 05:29 PM |
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just use the winch, attach it to some sort of grappling hook, throw it out (later revision could be some sort of rocket launch) and wind yourself back
ok, not serious but a winch motor is a good idea. suspect they will be slow and also suspect they aren't cheap. Any idea if a bec engine has
enough power in the electrics to drive one?
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peterriley2
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| posted on 28/10/05 at 06:47 PM |
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does anyone have a picture of their starter motor or chainsaw motor reverse? i would also like a bit more detailed description of how this is done!
can anyone help me out???
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ChrisGamlin
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| posted on 28/10/05 at 07:31 PM |
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Just posted this on the other thread but equally relevent here
Chris
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rayward
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| posted on 30/10/05 at 08:37 PM |
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anyone done it with a toothed belt?, what about a pulley from an aircon unit, where you apply voltage to engage it??
Ray
[Edited on 30/10/05 by rayward]
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G.Man
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| posted on 30/10/05 at 10:58 PM |
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Sprag clutch is a type of one way bearing..
Same as used on autorotation mechanisms on helicopters...
Allows the blades to keep spinning if the engine stops
Opinions are like backsides..
Everyone has one, nobody wants to hear it and only other peoples stink!
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Ratman
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| posted on 9/11/05 at 12:38 AM |
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I am somewhat embarrassed to suggest this crudity.. but.. How about a starter motor with an extended shaft that is knurled near the end. Then some
hinging device which will bring the knurled part of the shaft in contact with one of the rear tyres. Remember.. “how often are you going to use
it”!!!. I had imagined the operation would be controlled with a handbrake type of leaver with a thumb switch on it. The support frame for this
reverser could be designed to retract the nasty knurled thing out of site as part of it’s deployment. There was a generation of mopeds that used this
principle as part of the main drive train, so it is not exactly breaking new ground. Cheers, Brian
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