2-speed systems (R-D, dog-clutch or derailleur changing)
- Thread starter Miles
- Start date
Variable Gears - Logos 1908
This is photographed from my own copy.
There is a recent reprint of this book (print on demand) but it's completely useless - no illustrations, just scanned to OCR with no corrections or attempt at retaining the layout
This is photographed from my own copy.
There is a recent reprint of this book (print on demand) but it's completely useless - no illustrations, just scanned to OCR with no corrections or attempt at retaining the layout
This is one is just a curiosity. I made this proof of concept for fun, a few years ago. As far as I know, it hasn't been done before....
It's a 2 speed retro-direct gearbox that uses the sun gear for input and either the planet carrier or the ring gear for output.
The sun gear has 24t and the ring gear 72t so, the output from the ring gear gives a ratio of 3:1 and the output from the planet carrier gives a ratio of 4:1.
It's a 2 speed retro-direct gearbox that uses the sun gear for input and either the planet carrier or the ring gear for output.
The sun gear has 24t and the ring gear 72t so, the output from the ring gear gives a ratio of 3:1 and the output from the planet carrier gives a ratio of 4:1.
Attachments
Marc S.
100 W
Did any of the RC croud here heard of the Tiwamatic of German engeneer Tilman Wallroth? Sold in the early 90', it was/is a continous automatic transmission for 1:8 RC buggys.
Here is the German patent fom 1986: http://worldwide.espacenet.com/publicationDetails/biblio;jsessionid=UqPDpobslISwtFLBBz0+gg4n.espacenet_levelx_prod_0?CC=DE&NR=3504904A1&KC=A1&FT=D&ND=&date=19860814&DB=&locale=en_EP
Gear ratio is about 1:1.4 to 1:3.2. Power figures where 1.5 hp (1.100 W) at 10.000 to 25.000 rpm.
Not too shabby for such a small unit:
The original technical drawings from the patent application:
Here is the German patent fom 1986: http://worldwide.espacenet.com/publicationDetails/biblio;jsessionid=UqPDpobslISwtFLBBz0+gg4n.espacenet_levelx_prod_0?CC=DE&NR=3504904A1&KC=A1&FT=D&ND=&date=19860814&DB=&locale=en_EP
Gear ratio is about 1:1.4 to 1:3.2. Power figures where 1.5 hp (1.100 W) at 10.000 to 25.000 rpm.
Not too shabby for such a small unit:
The original technical drawings from the patent application:
Attachments
bobc
10 kW
Pondering this gearing issue, I wondered if anyone had thought to use an epicyclic box. You could combine a fair amount of gear reduction with a 2 speed box by making 2 planetary stages, and select the gear by stopping the selected ring with a pawl or dog. The rings and spurs are available e.g. from HPC gears in UK; here are a couple of suggestions with about 50% gearing hikes.
The input goes into the 2 suns. The 2 planets are held in line with the suns on the output shaft. The 2 rings just spin on the planets, except you stop one to select that gear. It can run in a bucket of oil & the planets sit on needle roller bearings.
There's no tricky alignment ( it's self aligning), no sliding things carrying torque or force & all the tricky parts easy to find on line....
apologies if this has been gone through already....
The input goes into the 2 suns. The 2 planets are held in line with the suns on the output shaft. The 2 rings just spin on the planets, except you stop one to select that gear. It can run in a bucket of oil & the planets sit on needle roller bearings.
There's no tricky alignment ( it's self aligning), no sliding things carrying torque or force & all the tricky parts easy to find on line....
apologies if this has been gone through already....
bobc
10 kW
hmmmm, the reverse select does nail the gear selection worries, and having a single epicylic gear halves the cost, the problem would be sourcing suitable ratchet/freewheels/sprags
I made a reverse select system once, I used a big 2 pole changeover switch in 2 of the motor leads - worked lovely but the switch was huge and expensive itself (but a suitable reversing motor controller would solve that little problem)
As ever the core technology is let down by the ancilliary parts
I made a reverse select system once, I used a big 2 pole changeover switch in 2 of the motor leads - worked lovely but the switch was huge and expensive itself (but a suitable reversing motor controller would solve that little problem)
As ever the core technology is let down by the ancilliary parts
bobc
10 kW
Miles, idly pondering this the other day, it occurred to me that a brake disc could be put on the "high speed" ring and a ratchet on the lowspeed, you'd select top gear by squeezing a brake caliper (copy of the brake bands they use in auto transmissions).
You'd get the same smooth "blurry" gear change you get with an auto box.
If the sun pinions went on an outrunner shaft, the epicyclics would take care of the primary reduction, the brake would give you 2 gears, then take a chain to a left side freewheel. Something I should look at? What ratio change would be most useful on a 2 speed?
Bob
You'd get the same smooth "blurry" gear change you get with an auto box.
If the sun pinions went on an outrunner shaft, the epicyclics would take care of the primary reduction, the brake would give you 2 gears, then take a chain to a left side freewheel. Something I should look at? What ratio change would be most useful on a 2 speed?
Bob
Is there an animation somewhere like this? It sounds intriguing, and possibly doable.
bobc
10 kW
Done a drawing. For epicyclics you need at least 15 teeth or tooth form issues alter the PCD. So 2 epicyclic sets
1) 69 ring, 15 planets, 39 sun: ratio sun - planets is 2.77:1
2) 69 ring, 27 planets, 15 sun: ratio sun - planets is 5.6:1
That's a ratio spread of just over 2:1 and a decent primary reduction.
Here's a drawing for 0.8 module gears showing there's room for 6 M5 bolts to hold the planets cage together
This looks like a goer! I've chosen gears available from hpc gears in UK at near £14 each, the rings are £33 each.
A constructor would also need a stack of bearings, I'll check on availability of suitable stuff
1) 69 ring, 15 planets, 39 sun: ratio sun - planets is 2.77:1
2) 69 ring, 27 planets, 15 sun: ratio sun - planets is 5.6:1
That's a ratio spread of just over 2:1 and a decent primary reduction.
Here's a drawing for 0.8 module gears showing there's room for 6 M5 bolts to hold the planets cage together
This looks like a goer! I've chosen gears available from hpc gears in UK at near £14 each, the rings are £33 each.
A constructor would also need a stack of bearings, I'll check on availability of suitable stuff
bobc
10 kW
OK here's a picture that might make things clearer; the 2 suns spin on the motor shaft, the planets all go round together on the output shaft and the ring gears just sit on the planets. You stop a ring from turning to select that gear.
Hi Bob,
Looking at the HPC catalogue. The 75t ring gear is the same stock O.D. as the 69t (of course, you can turn the 69t down more..) Just saying that another possibility, if someone wants as wide a ratio as possible, might be:
75t annulus, 15t sun, 30t planets
75t annulus, 45t sun, 15t planets
Ratios of 6 & 2.67
Differential ratio of 2.25
Still allows 3 planets in each set.
Haven't checked the clearances yet, though...
Looking at the HPC catalogue. The 75t ring gear is the same stock O.D. as the 69t (of course, you can turn the 69t down more..) Just saying that another possibility, if someone wants as wide a ratio as possible, might be:
75t annulus, 15t sun, 30t planets
75t annulus, 45t sun, 15t planets
Ratios of 6 & 2.67
Differential ratio of 2.25
Still allows 3 planets in each set.
Haven't checked the clearances yet, though...
bobc
10 kW
Yeah good one
All still divides by 3 to keep life simple
clearances are only going to get better/easier as you get bigger
All still divides by 3 to keep life simple
clearances are only going to get better/easier as you get bigger
bobc
10 kW
Miles said:
Ahhh - if only I had the time/money/need I'd start making one of these like a shot, but I have to stop starting new projects!!!
If somebody out there wants to start building then it should indeed get its own thread
Joe T.
100 W
Yah know…. A Thud 2speed concept would be quite easy to adapt to a GNG/LR type of setup. Recently I have been wishing I could get more top speed out of my bike. My problem is the low range is right where I need it to be as I mostly ride in the woods. But…. Some times I need to out run a storm and my 20 MPH max top speed is begging for more. The power is there I just don’t have the gearing.
All that would need to be done would be add a second drive and chain on both the jack shaft and the crank. A selector on the jack shaft to pick the drive gear and poof! Instant overdrive. You could make high range 360% over low range so there would be no overlap. The rear, N360 in my case, would do its job as normal. Shifting into high on the motor and low on the bike would make a seamless transition.
Just thinking out loud here.
All that would need to be done would be add a second drive and chain on both the jack shaft and the crank. A selector on the jack shaft to pick the drive gear and poof! Instant overdrive. You could make high range 360% over low range so there would be no overlap. The rear, N360 in my case, would do its job as normal. Shifting into high on the motor and low on the bike would make a seamless transition.
Just thinking out loud here.
wineboyrider
1 MW
Perhaps a sram dual drive?Joe T. said:
friendly1uk
1 MW
I used to like the daf variomatic. 60mph in forward and 60mph in reverse. Conical gears and a belt, with centrifugal regulator I was told. All I know is... 60mph in reverse! lol
samsavvas
100 W
Hi Miles et al,
I haven't read the whole thread and I may have misunderstood the challenge you have raised, but I wondered if you could simply use something like the old Sachs Orbit 2-speed rear derailleur/hub gear combination. I have used such an outfit in combination with a BBS-1 very successfully.
Sam.
I haven't read the whole thread and I may have misunderstood the challenge you have raised, but I wondered if you could simply use something like the old Sachs Orbit 2-speed rear derailleur/hub gear combination. I have used such an outfit in combination with a BBS-1 very successfully.
Sam.
Joe T.
100 W
wineboyrider said:
I already have that space used up with the N360.
