Could someone point me to some information about what metals I could use for
king pin bearings on a small, electric-motor-assisted, adult trike I'm
planning to build?
I was thinking of a tubular, square, thickwalled aluminum axle, and two mild
steel plates bolted top and bottom to each end of this with holes bored top
and bottom and a thick aluminium rod turned to fit into the holes of these
plates (trunnions?) and then be drilled and tapped at the correct angles for
the M12 HT steel bolts for stub axles.
In other words, with good lubrication, is aluminium rod OK in steel bushes?
There will be little rotational motion, and with a large bearing surface,
shock loads should be no bother.

John Riley wrote in message
...
Could someone point me to some information about what metals I could use
for
king pin bearings on a small, electric-motor-assisted, adult trike I'm
planning to build?
I was thinking of a tubular, square, thickwalled aluminum axle, and two
mild
steel plates bolted top and bottom to each end of this with holes bored
top
and bottom and a thick aluminium rod turned to fit into the holes of these
plates (trunnions?) and then be drilled and tapped at the correct angles
for
the M12 HT steel bolts for stub axles.
In other words, with good lubrication, is aluminium rod OK in steel
bushes?

Aluminium in mild steel is about the worst combination I could envisage,
especially with the possibility of dirt ingress. Poor friction coefficients,
rapid wear and galvanic corrosion are just some of the issues. Hardened
steel in aluminium bearings is ok if the system is enclosed and well
lubricated such as inside an engine, camshafts and piston gudgeon pins being
examples. King pins are usually case hardened steel pins in bronze bushings
or roller bearings with dirt seals at each end and provision for lubrication
via grease or oil nipples.

You'd never choose aluminium over steel for a load bearing axle or pin
anyway. Why go for a soft weak material over a hard strong one?
--
Dave Baker

by "bearings" the OP has apparently selected the sub-set of bearings
that all involve one plain metal or alloy running inside another plain
metal or alloy, basic principle of this is to maintain a fairly regular
difference in hardness between the two materials, eg if one is super
hard the other must be hard, if one is hard the other can be soft, but
the main point is off the top of my head I cannot think of a single
plain bearing application that does not have some sort of lubrication,
even if it is only a pickup ring in an oil bath and grooving...

for an adult trike why reinvent the wheel? why not simply specify off
the shelf standard ball / roller / taper bearings, esp sealed ones.....

On Mon, 23 Jan 2006 15:13:25 GMT, "John Riley"
wrote:

Could someone point me to some information about what metals I could use for
king pin bearings on a small, electric-motor-assisted, adult trike I'm
planning to build?
I was thinking of a tubular, square, thickwalled aluminum axle, and two mild
steel plates bolted top and bottom to each end of this with holes bored top
and bottom and a thick aluminium rod turned to fit into the holes of these
plates (trunnions?) and then be drilled and tapped at the correct angles for
the M12 HT steel bolts for stub axles.
In other words, with good lubrication, is aluminium rod OK in steel bushes?
There will be little rotational motion, and with a large bearing surface,
shock loads should be no bother.


Buy a bicycle for $20 from a garage sale (perhaps carboot sale, given
your spelling of "aluminium"), cut it up and use the headset and
ball bearings it contains. It will be a lot easier to steer if it
has good geometry and good bearings.

On Mon, 23 Jan 2006 14:09:45 -0600, Don Foreman
wrote:

On Mon, 23 Jan 2006 15:13:25 GMT, "John Riley"
wrote:

Could someone point me to some information about what metals I could use for
king pin bearings on a small, electric-motor-assisted, adult trike I'm
planning to build?
I was thinking of a tubular, square, thickwalled aluminum axle, and two mild
steel plates bolted top and bottom to each end of this with holes bored top
and bottom and a thick aluminium rod turned to fit into the holes of these
plates (trunnions?) and then be drilled and tapped at the correct angles for
the M12 HT steel bolts for stub axles.
In other words, with good lubrication, is aluminium rod OK in steel bushes?
There will be little rotational motion, and with a large bearing surface,
shock loads should be no bother.


Buy a bicycle for $20 from a garage sale (perhaps carboot sale, given
your spelling of "aluminium"), cut it up and use the headset and
ball bearings it contains. It will be a lot easier to steer if it
has good geometry and good bearings.


Or use steel rod in aluminum bearings, or bronze bearings, or nylon,
or HDPE, or herdwood boiled in oil, whatever. Do NOT use aluminum
shaft in steel bearing (bushing)

I use headsets..

Thanks for that. Can you explain why not aluminium shaft in steel bushing?
Is there some rule of thumb that I'm not aware of?
Or does something nasty happen that I've not thought of?
I have rethought and will probably use aluminum in aluminum, anyway.
The shaft will be someting like 1" in diameter. The bearing surfaces will be
large and well lubricated with heavy grease with a cover to prevent ingress
of dirt as much as possible. I need a lot of meat to screw the M12 HT
bolt stub axles into it, and also insert the control arms.
I've seen headsets used for the two front steering bearings. It just seems
a rather complex way of doing what I want. I want to avoid welding if I
can, and I want it to be light and cheap. These bearings don't need to be
very free, in fact a bit of friction in them will be advantageous.
Save me installing a steering damper.


clare at snyder.on.ca wrote in message
...
On Mon, 23 Jan 2006 14:09:45 -0600, Don Foreman
wrote:

On Mon, 23 Jan 2006 15:13:25 GMT, "John Riley"
wrote:

Could someone point me to some information about what metals I could use
for
king pin bearings on a small, electric-motor-assisted, adult trike I'm
planning to build?
I was thinking of a tubular, square, thickwalled aluminum axle, and two
mild
steel plates bolted top and bottom to each end of this with holes bored
top
and bottom and a thick aluminium rod turned to fit into the holes of
these
plates (trunnions?) and then be drilled and tapped at the correct angles
for
the M12 HT steel bolts for stub axles.
In other words, with good lubrication, is aluminium rod OK in steel
bushes?
There will be little rotational motion, and with a large bearing surface,
shock loads should be no bother.


Buy a bicycle for $20 from a garage sale (perhaps carboot sale, given
your spelling of "aluminium"), cut it up and use the headset and
ball bearings it contains. It will be a lot easier to steer if it
has good geometry and good bearings.


Or use steel rod in aluminum bearings, or bronze bearings, or nylon,
or HDPE, or herdwood boiled in oil, whatever. Do NOT use aluminum
shaft in steel bearing (bushing)

I use headsets..