alternate drive coupler

[mobile_bob]

as most know, i have a changfa 195, running direct drive st7.5 at 1800rpm
because this started out to be a test mule for various driven components, there are many pulley grooves most
folks would never have a need for.

i wanted the ability to drive at low speed as well as 1800rpm, and at lower speeds the changfa's are hard on lovejoy
couplers, so i designed a solution to the problem that allows for low speed running, angular misalignment of several degree's
as well as offset of 10's of thousands of an inch with no problems, as well as having a failsafe break away function should
one try to connect to the grid out of phase.

what i came up with is a standard 4 inch tubeless tire and steel rim running inside a 1 ton ford disc brake bowl section of the rotor.
the rotor came from my brake guy, he has a pile that are too far gone for turning so he cuts the rotor off and leaves the bowl section for me.

the 4 inch wheel and a 2.25 x 4" 4ply tire will just barely fit within the bowl, and when aired up make a really nice coupling

the 4 inch wheel uses 1-3/8" od brgs, so the bore size will accept a stub shaft of the same size.

i then machined the main drive pulley to register to the changfa 3 bolt pattern on the flywheel, it is attached with a spacer to
get out past the big ass nut that retains the flywheel.

after that was fitted, i removed it and added a taperlock bushing to capture the 1-3/8" stub shaft that is welded into the bore
of the 4 inch wheel. so now there is a 4 groove pulley and a stub shaft mounted tubeless tire mounted

the st head has another  groove pulley attached to it, and to the pulley i mounted the disk rotor bowl, it is doweled and mounted
with countersunk grade 8 bolts

the two are mated together, and he tire is aired up to 30 psi

in testing the unit just starts to creep at a bit over 8kwatts output (which is overload for the st7.5 anyway), this unit can be tailored
to break away by adjusting tire air pressure at any output desired.

in operation it runs dead true, no vibration, and does not gain any heating, which is an indication of alignment being very good.

the engine can be run at any rpm from 1000rpm to 2200rpm without issues.

just an alternative drive system that i thought i would share with those interested.

hopefully the pictures illustrate the unit well enough to understand what i didn't do well in print.
pics are very good, might have to take more?



bob g

[mobile_bob]

although it is not well illustrated in the pics, there was another reason for the setup

when you direct drive a genhead, and also try to drive other components with belts
it is far to easy to "trap" the belts, makeing it necessary to remove the coupler, or slide
back the genhead to get the belts out when they need changed.

the system in place on this unit is what uses what is known as a double set of AA belts

AA belts have a hexagonal crosssection, much like two A section belts bonded back to back
this allows for them to drive on both side of the belt and to be used in serpentine applications.

as such the belts go over the top of the engine pulley, then down under both left and right alternators
and up over the refrigeration pump.

both belts can be changed in under 2 minutes, and because of the routing the alternators get a 180 degree wrap
each, the drive pulley gets 120 degree's, and the refrigeration pump gets 90 degrees (which is adequate).

belt tension is therefore reduced, no need to run bango string tight, very low heating under full load would indicate
very low slippage as well.

i am thinking of mounting a belt driven automotive waterpump under the main xmember, allowing for a reroute of the belts
which would greatly increase the belt contact over the drive pulley on the engine.  haven't decided yet if i will include such a pump
or not just yet, because i don't know for sure what a small block chevy waterpump draws in hp to operate.  it might be that i could reduce the hp required by the pump and also reduce its flow rate by grinding off every other vane from the impellor? another project
of another day, although something that would be useful for moving the btu's away to a remote thermal storage tank.

bob g

[veggie]

Hi Bob,

That's a neat idea. The sidewall of the tire would provide great torsional buffering for the firing pulse of the Changfa at lower rpm's.
The stiffness of the coupling can be adjusted by air pressure.
Very creative.

Veggie