shaywez
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| posted on 5/6/05 at 07:27 PM |
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drivetrain
Hi, i am considering building a MK indy with a bike engine as my next project, i have not long finished a Luego velocity. I have a few simple
questions though to do with the drivetrain required. Iunderstand the principle of fitting a bike engine and utilising the sierra propshaft and diff
(does it need to be LSD), but how is a reverse gear achieved? Also i assume you have a clutch pedal the same as a car, is this right? All
information appreciated. Some questions may seem simple but i am trying to build up a mental picture/list of my requirements at present, thanks
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rayward
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| posted on 5/6/05 at 07:32 PM |
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Hi,
Yes you still have a clutch pedal(it just connects via cable or hydraulics as it would have done on the bike), as for reverese gear you can either go
for reverse gearbox(reverson etc) which has two flanges one to engine one to diff and sits in middle of prop etc, or have an electric motor which
drives the propshaft via a toothed gear/sprocket and is not engaged when going forwards.
Doesnt need to be LSD but will help!
Ray
[Edited on 5/6/05 by rayward]
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ChrisGamlin
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| posted on 5/6/05 at 08:16 PM |
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Just a note though, you don't actually NEED a reverse for road use if you don't mind pushing when you want to go backwards, there's
no SVA / MOT requirement. It may seem odd to think about it without a reverse, but once you've driven it for a bit you get used to it.
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tks
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| posted on 7/6/05 at 07:33 PM |
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strange isn't it??
aren there hills in england??
i still can find no car with an electrical reverse explanation etc...
think an wiper motor could do the job??
TKS
The above comments are always meant to be from the above persons perspective.
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smart51
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| posted on 7/6/05 at 07:51 PM |
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my dad had an ordinary car that couldn't get into reverse. He managed just fine. You just had to choose spaces in car parks carefully. Park
facing up hill if you can.
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Alez
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| posted on 8/6/05 at 06:53 AM |
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BTW, is a LSD any heavier than a conventional diff?
Cheers,
Alex
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Bob C
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| posted on 8/6/05 at 11:56 AM |
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LSD generally a bit heavier - they have more stuff in! quaife ATB & torsen a couple of kgs or more heavier, clutch, viscous types probably a kg or
so - all estimates. I have a quaif & it's a big solid lump of steel where the open dif has quite a lot of air.....
Electric reverse - I'm making a starter motor powered propshaft centre bearing. This will also do handbrake, speedo sensor & feature a
rubber donut for "cush drive" The gear diam of 200mm is a bit smaller than your average starter ring (so it will fit in my trans tunnel).
To get an idea of what to expect put your car in 4th gear & wind forward on the starter motor!
The aspect that's troubling me most is how to control it - the power electronis is easy enough (it's my job) but how does the driver
control the speed? you can't use the throttle or the motor will race (it's in neutral [interlocked!]) - any 'joystick' or hand
control will be in the wrong place when you twist round to turn the other way. Best plan I've come up with is to hook your foot under the
throttle pedal & pull up to go backwards. Any (better) ideas would be welcome!
hardest part of job is sourcing the big gear - I've tried laser & waterjet cutting places but they won't touch it; next port of call
is an obscure distant in-law who makes cogs for a living & might be able to slip it through work as a foreigner or at cost. The rest of it is done
& chassis mounts & front propshaft all complete.
I'll slip a pic on the archive or my website when I get the gear.
cheers
Bob
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ChrisGamlin
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| posted on 8/6/05 at 12:10 PM |
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Daft idea possibly, but what about putting in a switch to enable the starter motor, then having a potentiometer on the clutch pedal?
Put car into neutral so clutch itself has no effect, then use the clutch pedal as an accelerator for the reverse once you've thrown the switch
to turn it on.
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tks
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| posted on 8/6/05 at 01:06 PM |
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..
The idea is lose on many area's...
Thirst there is no potentio meter in the world that can cope with 1kW...
and if there is then it would be more heavier then the car itself......
we are talking about huge amounts of power... and more if you give to little power to the engine.... (you hold the crank)
i'm surely gonna build an reverse....an electrical / digital one..
to fool the sva man and to charge battery etc while reversing i'm gonna program the cpu's to automaticly rise engine speed to 3000rpm
etc..
the only way to go is to do it with PWM and some huge mosfets..(5x buz 11 in parallel and some huge alu fan cooled thing (amd athlon etc..)
and then i think i can cope with 500watts of engine power.. 5x 30 amps = 150amps *12 = 1800Watts butt!! an safety factor of 3..
half an horse power.. my goal is one BHP..
of engine power (800watts)..but lots of torque....to move the car..
potentio meter can work.. but not as direct motor drive.....
Soow needings/skills are:
- microcontroller (pwm outputs,adc)
- potentiometer
- couple of resistors (10K,1K)
- potentiometer same amount of the both but a normal adjustable one..
- programmer/program.
- mosfets to cope with 150 / 300Amps
- maybe some power diodes....
When i'm at this stage will let you all know..
Tks..
PWM stands for Pulse with modulation..
in fact what we do to control the rpm is switch the engine on and then off and then on again..the duration of the on pulse will then be
'connected' to some % rpm amount.. of the engine..
but untherload the amps rise sky high..
and in fact what we need is that we can cope with the biggest hills that we can meet...
you don't want that you are giveing full reverse and the car goes forward!!!
LSD's
YES they are much heavier but it depens on type of it.
The visco lsd (sierra ones) i guess they weight 5kgs more..)
but take a Beamer one or MB...they weight so much thats its a pain in the arse to get it down unther are car...
i think 20Kgs.. the weigth there would be in the heavy plates/springs etc..
[Edited on 8/6/05 by 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 8/6/05 at 02:53 PM |
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Hi Chris,
problem with that is that it's instinctive to push the clutch to the floor when you want to stop.... ooops!
hi tks
obviously you'll need more than just a pot (hence mention of power electronics)
However it sounds like you're thinking of over-engineering - PWM duty cycle control is all you need (the old human brain will close the loop for
you!) so a simple single op-amp circuit can be used to create a self oscillating pulsewidth modulator - + some monster mosfets & diodes, peice of
cake.
I'm certainly not thinking about reversing up kerbs or 1 in 3 hills, 1kW is plenty power for me. I'll probably spec it for 300A or so,
limit the current by limiting the duty cycle.
Alternatively use something like the unitrode 3843, but I think even that's way OTT
cheers
Bob
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Bob C
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| posted on 8/6/05 at 02:58 PM |
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tks - just had another look at your post, you seem to be worried about the battery going flat while reversing. I'm reckoning that's not an
issue - I can't remember when I last reversed more than 3 metres...
I think starting the engine will be much harder for the battery than parallel parking!
Bob
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ChrisGamlin
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| posted on 8/6/05 at 03:52 PM |
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quote:
Originally posted by Bob C
Hi Chris,
problem with that is that it's instinctive to push the clutch to the floor when you want to stop.... ooops!
Err, could you not just wire it up the other way then, bringing the clutch up to increase speed? I guess you'd have to put in some kind of extra
switch to only allow you to activate the reverse when the clutch is fully depressed, but not insurmountable?
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Rorty
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| posted on 9/6/05 at 05:29 AM |
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I fitted an electric reverse once that was operated by a micro switch on one of the steering wheel spokes.
Laser or water-cutting a gear for this purpose is well within posibilities; just supply them with a suitable DXF file. Why won't they touch it
Bob?
Have a look at electric wheelchair and scooter parts catalogues. They lead the way in hi-torque, compact and light-weight stuff, plus, they have all
sorts of nice little controllers etc.
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 9/6/05 at 09:46 AM |
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Rorty - I tried the laser company along the road from work - they don't know me from adam, so I can understand them not wanting to open a can of
worms in an application they're not experienced with. I can still try the company my brother uses if the machining options come to nothing. I
think laser/water is potentially OK: with only a 10 tooth pinion it's bound to be noisy anyway. Fair point re: wheelchair stuff - but I've
been seduced by the solenoid gear engagement system that comes with every starter motor...(plus they're virtually free....)
Bob
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ChrisGamlin
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| posted on 9/6/05 at 09:51 AM |
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Have a look on Ed Cane's website, www.westicles.net, he built an electric reverse from a Scooby
starte motor ISTR, its been very reliable for several years and quite powerful compared to most other electric reverses Ive seen.
Chris
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tks
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| posted on 27/6/06 at 10:59 AM |
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Reverse
BOBC
want to build the reverse because its needed over here to pass the SVA (over here)..
sow can you give me some more / better hints??
only thing i need is a scheme to build up.
i already have one buz11 wich is connected to a microcontroller and the acc pedal
The above comments are always meant to be from the above persons perspective.
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kb58
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| posted on 27/6/06 at 01:39 PM |
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Why do you need to control reverse speed at all?
When you engage it, have a circuit that ramps the controller PWM up smoothly to your "top speed" of maybe 1mph. That's it... I
can't think of a situation where you'd need to have different speeds.
[Edited on 6/27/06 by kb58]
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Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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tks
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| posted on 27/6/06 at 02:54 PM |
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the engaging will be automatic
i will use a one way bearing...
when the speed of the bearing/motor is higher then the speed of the axle then
it will auto engage.
sow it takes away another nasty problem..
Tks
now i need a suitable motor and the controller circuit..
in the controller circuit there will be build in the speed smoothness..
because the motor and the controller wound´t last long if enabled fast..
also i don´t like surprises thats the reason i wat to controll those pulses..
tks
[Edited on 27/6/06 by tks]
The above comments are always meant to be from the above persons perspective.
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tks
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| posted on 4/7/06 at 04:38 PM |
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Bob C
could you help me a bit? need a Solidstate scheme to control a CBR 600 starter motor..
Tks
The above comments are always meant to be from the above persons perspective.
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