chancer
ɔ ɥ ɐ u ɔ ǝ ɹ
Well that changes things!
Planning/Imminent build of 4x4 kart
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Actually worm gear rear ends are quite popular on heavy duty OTR heavy haul trucks, and earth moving equipment. On the lighter side of things Cushman golfcarts, haulsters and trucksters still use them, and yes you can push them quite easily. My 1971 Am General M35a2 6x6has 3 of them and they roll quite well. The weak area on the snowblower drives is the aluminum casting case.
Denny
that does change things, at first after I looked these things up, i thought they would have wheel clutches or somwthing, but the cushman axles look like just what you described
Denny
Canned Monster
Yup, see there you go worm gear drive. 
Denny
Denny
Said it before and think I should say it again.. it's a question of the lead angle.!
I might be falsely assuming the worm in question is a single start in which case it's lead angle is at least twice as big as I think it is (and it indeed will get turned; but if so in BOTH directions)
The Cushman worm is IIRC a fourstart worm with lead angles well above 15°
That tiller looks more like <5° to me...
I'd love to see the worm... maybe it is indeed a multi start worm in which case I'll have to apologize.
'sid
I might be falsely assuming the worm in question is a single start in which case it's lead angle is at least twice as big as I think it is (and it indeed will get turned; but if so in BOTH directions)
The Cushman worm is IIRC a fourstart worm with lead angles well above 15°
That tiller looks more like <5° to me...
I'd love to see the worm... maybe it is indeed a multi start worm in which case I'll have to apologize.
'sid
ezcome-ezgo
G'me sumthin to write on
This is interesting. And the lead angle effectively changes the ratio also? I had never really thought about this before.
it does..
it's just like a thread pitch the shallower the lead angle the smaller the pitch.
take a 1" bolt for example... a fine threaded bolt advances 1/12" per revolution (12 TPI)
a coarse threaded bolt 1/8" per revolutions (8 TPI)
(those will be our worms)
now take a roller skate wheel as our cog wheel (rubber the bolt threads can cut into
)
and for simplicity reasons let's assume it's circumference is 7"
to make it rotate exactly once we need either 56 rotations of the UNC bolt (56:1)
or 84 rotations of the UNF bolt (84:1)
with shallowing the lead angle alone (increasing the TPI of the bolt) we changed the ratio from 56:1 to 84:1
'sid
it's just like a thread pitch the shallower the lead angle the smaller the pitch.
take a 1" bolt for example... a fine threaded bolt advances 1/12" per revolution (12 TPI)
a coarse threaded bolt 1/8" per revolutions (8 TPI)
(those will be our worms)
now take a roller skate wheel as our cog wheel (rubber the bolt threads can cut into
)and for simplicity reasons let's assume it's circumference is 7"
to make it rotate exactly once we need either 56 rotations of the UNC bolt (56:1)
or 84 rotations of the UNF bolt (84:1)
with shallowing the lead angle alone (increasing the TPI of the bolt) we changed the ratio from 56:1 to 84:1
'sid
thendrix
New member
If it were me I would look closer at an ATV diff. Maybe even the whole driveline. You want independent suspension, shaft drive, enough travel to run 20" tires. Gearing might be a bit high but they also have 4wd. Seems like a good way to go to me would be a 400 or so cc with a blown engine. Rob what you need, sell what you don't. I'm Tyler BTW. Just joined today and really have enjoyed reading this thread so far.
Flyinhillbilly
The great cornholio
I'd like to add that the steering in your car is worm gear (unless it's rack and pinion) and I turn those all day every day at the tire rather than the steering wheel with a much steeper gear ratio than what's being discussed here.
I also agree that ATV diffs would be the berries for this build IMO
I also agree that ATV diffs would be the berries for this build IMO
it sure looks like a dual start worm...
and that means it's indeed twice the angle I was thinking...
my apologies!
Anyways, that raises a question.. why doesn't it work in reverse *shrugs*
I mean just think about a kart you maneuvered into a tree and you cannot roll it back without wrecking the gearbox?
that'd not be nice...
Flyinhillbilly I don't know about your car... but mine's steering powered by a servo motor
'sid
and that means it's indeed twice the angle I was thinking...
my apologies!
Anyways, that raises a question.. why doesn't it work in reverse *shrugs*
I mean just think about a kart you maneuvered into a tree and you cannot roll it back without wrecking the gearbox?
that'd not be nice...
Flyinhillbilly I don't know about your car... but mine's steering powered by a servo motor
'sid
chancer
ɔ ɥ ɐ u ɔ ǝ ɹ
What kind of car?
Flyinhillbilly
The great cornholio
X2 I run a front end shop for a living and haven't encountered one of those yet.
chancer
ɔ ɥ ɐ u ɔ ǝ ɹ
You know Alex. It is probably a Google Driverless all electric car! seriously though???
jeez kids, I know it's electrohydraulic and not JUST a motor
(but that's in fact the case for some smaller Fiats and such [basically every car with a 'CITY' button to ease parking])
What I wanted to say is: powersteering is a very different animal ..
'sid
(but that's in fact the case for some smaller Fiats and such [basically every car with a 'CITY' button to ease parking])
What I wanted to say is: powersteering is a very different animal ..
'sid
sid, no need to apologize
so what I've gained thus far would be that I am going to use the worm gears knowing that there is a considerable risk of their implementation
I have also decided to ditch the independent sus. originally designed for a SAS setup. The indep. was going to be too difficult to build (for me) and expensive, etc. besides solid axles are more basic and generally cheaper. however the story may be different because I have to build my own. This shouldnt be too complicated, the worm gears coupling into a wider shaft turning inside a tube, at the ends the hubs. For the steering axle, I'll create a simple drag link steering and use C channel as clevis and spindle, then use bearings in both the clevis and the spindle.
As for the suspension side of things, I need to keep it light, so I chose a simple 2 link with one central link and a pan hard bar to hold the axle in place (yellow=suspension link) The end of the main link that is attached to the axle is fixed and the end that attached to the frame crossmember (not drawn yet) will be on a high misalignment heim joint (this joint dictates amount of articulation) Then the pan hard bar sits in the same direction as the axle and will be adjustable with heim on one end (not drawn yet)
although the engine now has to be mounted significantly farther forward, sacrificing driver room, it was the only way to have the motor mounted without adding another RAGB. This keeps the motor linked to the fixed part of the DS for a reasonably short length before it gets to its ends. the DS ends will be expandable u joints
note: many things have not been drawn yet including any steering components
thoughts?
so what I've gained thus far would be that I am going to use the worm gears knowing that there is a considerable risk of their implementation
I have also decided to ditch the independent sus. originally designed for a SAS setup. The indep. was going to be too difficult to build (for me) and expensive, etc. besides solid axles are more basic and generally cheaper. however the story may be different because I have to build my own. This shouldnt be too complicated, the worm gears coupling into a wider shaft turning inside a tube, at the ends the hubs. For the steering axle, I'll create a simple drag link steering and use C channel as clevis and spindle, then use bearings in both the clevis and the spindle.
As for the suspension side of things, I need to keep it light, so I chose a simple 2 link with one central link and a pan hard bar to hold the axle in place (yellow=suspension link) The end of the main link that is attached to the axle is fixed and the end that attached to the frame crossmember (not drawn yet) will be on a high misalignment heim joint (this joint dictates amount of articulation) Then the pan hard bar sits in the same direction as the axle and will be adjustable with heim on one end (not drawn yet)
although the engine now has to be mounted significantly farther forward, sacrificing driver room, it was the only way to have the motor mounted without adding another RAGB. This keeps the motor linked to the fixed part of the DS for a reasonably short length before it gets to its ends. the DS ends will be expandable u joints
note: many things have not been drawn yet including any steering components
thoughts?
chancer
ɔ ɥ ɐ u ɔ ǝ ɹ
On a 4wd Application It may be a good thing having the driver further forward. Adding weight to the front Axle
Lostboy
New member
You have to use something other than a lawnmower engine and a centrifugal clutch. I'm still wanting to build a cart based off of a hondamatic. Probably the little one like a 400. No reverse, but you'd have a low and high gear and probably about 30hp.
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www.lostboysatomicgarage.com
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www.lostboysatomicgarage.com
lurch9
New member
How are the yellow link bars connected to the axles? If it's just the 2 links, the torque of the rear axle will destroy them quickly. I would suggest an upper 3rd link running to the frame near the apex of the lower links.
Also, your steering link up front needs to be the same length as Panhard bar or you will get bumpsteer.
Also, your steering link up front needs to be the same length as Panhard bar or you will get bumpsteer.
SkidooTNT
New member
Go to a true 3 link suspension.
2 link bars with rod ends on both sides and a panhard bar.
Will give you better articulation and is easer to fabricate.
2 link bars with rod ends on both sides and a panhard bar.
Will give you better articulation and is easer to fabricate.
Destroyed? If the pan hard holds the axle transversely and the big link holds it longitudinally, Where is the play? These components are not under a huge amount of stress/strain anyway with power being so limited.
If a three link suspension was used (two longitudinal and one pan hard, then the axle could pivot on the axis of the ends of the long links on the axle side (this pivot would be limited to the misalignment of the heim on the pan hard bar)
Since the main link on a 2 link setup is attached on the axle side with no pivot, there is no way that the axle can pivot on its own because its entire rotational movement is dictated on the single heim on the frame side. Because the single heim also allows pivot sideways (radius parallel to the ground) The pan hard bar prevents this without sacrificing suspension travel. This means that the only limit of the sus. travel is the single heim on the big link
...i think, but if it doesn't work, one can always add control arms
here's some other "one" link setups i've seen
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