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.).

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 ?

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?

How many Nm or ft/lb are needed to reverse a BEC slightly uphill ?

Would a couple of 18v cordless drills do it ?

Cheers

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

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

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

---

I'm away on the road this weekend, I'll post something when I get back.
cheers
Bob

They don't, it's called a sprag clutch. Should have gone to Specsavers.

It's not a ratchet type affair either.

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

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

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?

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.

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

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

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.

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

---

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

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?

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???

Just posted this on the other thread but equally relevent here

Chris

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]

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

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