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mahgnia
21st Feb 2016, 11:18 PM
I decided to construct a petrol-powered rope winch for various uses at home and on the land (3 in 1 slope to carry firewood uphill).
I have an old but still good 40cc Mistubishi brushcutter motor but to get it to drive a winch I need a very high ratio speed reduction gearbox.

I decided a good project would be to make a compact 3 stage epicyclic gearbox, 5:1 reduction on each stage, giving 125:1 total reduction. This gives 40 RPM output with a 5000 RPM input speed, which should suit the motor, which is also rated (new) at about 1.2 kW.
Anyway, some pictures:
The indexing fixture for cutting the planet gears. The sun gears were cut using the same fixture.
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Just finished the innards of the gearbox.
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Still to make the ring gear/housing and end plates/bearing supports.

The gears are MOD 1 sun 20T, planet 30T and the single shared ring gear will be 80T.

Andrew.

KBs PensNmore
22nd Feb 2016, 01:10 AM
Nice work Andrew, too technical for me ATM, maybe in 10 years or so.:2tsup:
Look forward to seeing the finished winch.
Kryn

Steamwhisperer
22nd Feb 2016, 06:35 AM
Great work Andrew.
I have to know, did you use loctite on the bearings or did you machine to tolerance.
Looking forward to the rest of the build.

Phil

Michael G
22nd Feb 2016, 06:52 AM
Great stuff - I'll be interested in how you tackle the ring gear.

Michael

mahgnia
22nd Feb 2016, 12:52 PM
Great work Andrew.
I have to know, did you use loctite on the bearings or did you machine to tolerance.
Looking forward to the rest of the build.

Phil,

All the bronze bearings were machined to an interference fit (roughly about 0.03mm/10mm dia) and pressed in, and then set up in the 4 jaw for boring and facing.

The planet gear pins were press fitted into the carriers with an interference fit (about 0.05mm/10mm dia).

All seems very solid, but the proof will be in the testing and running under load.

It was good practice for me to regularly machine to a tolerance, and also good testing for my home-made "20 ton" :rolleyes:press.

Andrew.

mahgnia
22nd Feb 2016, 01:00 PM
I'll be interested in how you tackle the ring gear.


Michael,

Yeah, still trying to work that one out....

Have to decide on a material to obtain/use. I am leaning towards grey cast iron to provide the balance of strength and machinability. Other alternatives are steel and aluminium.
Have also to decide how to cut the internal gear teeth. I could do it on the lathe manually with my spindle indexer fitting, but aluminium would be easiest, cast iron harder and steel would be very difficult. It would also keep the lathe out of use for anything else for quite some time.

Andrew.

.RC.
22nd Feb 2016, 04:09 PM
That is very impressive.

So where does the epicyclic come into it? Are the gears cut to an epicyclic profile rather then an involute?

mahgnia
22nd Feb 2016, 04:28 PM
RC,

The gear arrangement is epicyclic in that the planet gears rotate around the central input sun gear. The ring gear will be fixed, and so the output of each stage is taken from the planet gear carrier.
The tooth profile is involute.

Andrew.

.RC.
22nd Feb 2016, 04:41 PM
Thanks, that is what had me confused as a lot of publications simply call what you are building a planetary gear set (and thus was all I ever new them as) when it's proper name is what you have written.

https://en.wikipedia.org/wiki/Epicyclic_gearing

mahgnia
1st Mar 2016, 09:08 PM
More work done.

Obtained a $20 lump of 4E cast iron in almost the exact size needed for the ring gear.
Used a hole saw and lots of coolant to save the core for another project.
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Used the lathe as a manual shaper with my spindle indexer/spindle lock to cut the internal gear teeth on the ring gear. Hard, hard work! Going to take a few days to recover:oo:
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Test fitted the epicyclic gear assembly in the ring gear. Spins OK with a couple of slightly tight spots. Some deburring of the ring gear teeth should fix this.
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Andrew.

Michael G
1st Mar 2016, 09:13 PM
Impressive stuff!

Michael

KBs PensNmore
1st Mar 2016, 10:51 PM
Excellent work Andrew, and impressive, was wondering how you were going to do the inside, now I know. Never thought of using the tailstock!!!!
Kryn

jhovel
2nd Mar 2016, 02:28 AM
Outstanding effort! That must have taken hours and hours...
How did you go about grinding the 'shaper' tool for the internal teeth?
Thanks for showing us!

mahgnia
2nd Mar 2016, 09:24 AM
That must have taken hours and hours...
How did you go about grinding the 'shaper' tool for the internal teeth?

Joe,
It certainly did take hours and hours, and hours and hours....

I ground the form tool based on the tooth shape from an 80T MOD 1 gear, with slight alterations to provide clearance at the bottom of the tooth space being cut.

An 80T change gear from the lathe just slides into the ring gear as a test. This allowed me to see how accurate the tool form (and ring gear) was. Not perfect, but close enough (I think), with fairly consistent clearance around the ring gear tooth form.

Andrew.

jhovel
2nd Mar 2016, 03:05 PM
Thanks for that explanation, Andrew. Sounds simple, but I bet it took a lot of fiddling :) Having a ready 'go/no-go' gauge is also not something I thought of....

electrosteam
3rd Mar 2016, 09:04 AM
Andrew,
Add me to the chorus of admiration.
I am especially interested in the internal gear shaping, and curious just how the tailstock was used to mount the tool.

For the limited amount of shaping in the lathe that I have done the tool was mounted normally on the topslide and the saddle racked to apply the cut.

I wonder if you provide a more detailed description.
John

mahgnia
3rd Mar 2016, 10:28 AM
John,
The tailstock was only used to core out the cast iron block ready for boring.

The shaping was done as you describe with the tool in the toolpost and the saddle manually racked back and forth, to which my still sore arms and hands can attest.

Andrew.

mahgnia
7th Mar 2016, 10:40 PM
Gents,

The gear reducer is now completed.

I decided to alter the first stage to using 2 planet gears only, as this end has to cope with the lowest torque and highest speed. Less resistance, less noise, (and I made a mistake with the machining of the planet carrier of a couple of thou in the position of one of the planet shaft pin holes:rolleyes: causing the epicyclic gears to bind at one point in the rotation of the carrier)

I machined the end plates from some 2011-T6 aluminium, fitted the ball bearings to the input and output shafts, threw in some generous gollops of molykote grease, and closed it up with some M8 caphead bolts.

Seems to work very smoothly, with a slight amount of gear noise from the high speed end (expected this with spur gears).
Pictures:
361354361351361352361353


Next project is to attach the gearbox to the motor, and build the rope winch.

Thanks to all for the encouragement and compliments.

Andrew.

Steamwhisperer
8th Mar 2016, 05:25 AM
Fantastic thread Andrew I thoroughly enjoyed it, probably due to the minimal, perhaps even no use of loctite (a sign of a great machinist :D :2tsup:), but more likely because it is not the normal bit of machining we get to see from the shed at home.
Great stuff.

Phil

eskimo
9th Mar 2016, 09:32 AM
looks very impressive and going by the others commments it must have been a challenge.....but....I'm still at a loss how it works...:doh:

I will google a video or something for simulation...all good now I know

.RC.
9th Mar 2016, 06:28 PM
Would the cast iron have enough strength?

sacc51
9th Mar 2016, 10:37 PM
Many drills use planetary gearboxes, if you want to see how planetary gearboxes work, remove the gearbox from your cordless drill. You are the master Mahgnia, that is an extraordinary piece of work!

mahgnia
10th Mar 2016, 10:01 AM
Would the cast iron have enough strength?

RC,

I'm hoping that the cast iron will be strong enough.

There are several factors that may work in my favour here:
1. The gearbox is heavily oversized for the amount of torque I will be putting through it.
2. There are 4 planet gears in contact with the ring gear on stages 2 and 3(highest torque stage) spreading the torque load around the ring gear, not just a single point of force.
3. Each planet gear has about 5 teeth in contact with the ring gear at any time due to the curvature of the internal ring gear. This gives 20 ring gear teeth(out of 80) in contact at any time on stages 2 and 3.

I'll just have to see how it goes.

Andrew

mahgnia
12th Mar 2016, 06:15 PM
Gents,

Just completed the adapter to attach the gearbox to the motor.

Aluminium adapter (bell housing), steel centrifugal clutch drum pressed on to a cast iron gearbox input shaft adapter.


The relative sizes of the gear reducer and the motor can be seen.

On to the winch part....

Andrew

pcx
17th Mar 2016, 09:17 AM
What absolutely spectacular work. All I can say is "WOW".
Looks like Michael G has some competition.
Thank you for sharing.

Blu_Rock
19th Mar 2016, 10:30 AM
Great work Andrew, very impressive! Looking forward to seeing the completed winch. Any chance of a video of it working once finished?

mahgnia
20th Mar 2016, 06:35 PM
The winch drum is now just about completed, including my crappy welds. I cleaned them up as best I could on the lathe.

Took a bit of setting up in the lathe to get the bearing support on the drive shaft and the bearing socket at the other end fairly concentric and parallel.
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Should be OK as the drum will be rotating quite slowly
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Ready for the winch support frame.

Apologies for the poor pictures but the camera was in some strange mode....
Andrew.

mahgnia
7th Apr 2016, 12:24 AM
I haven't posted for a while but I've made a small amount of progress with the winch.
Pictures attached of the assembly mocked up on the bench.
It uses a tumbler gear type arrangement to provide forward, reverse and neutral drive to the drum.

Still needs a bit of neatening up, and a few parts including bearing retainer caps for the winch drum, base frame to hold it all together, locking (detent) mechanism for the drive direction selector lever, an escapement mechanism for the drum to lock it in case of drive disengagement (this will need to work on either direction), and various accessories for the motor like fuel tank, throttle lever, shut off switch etc.

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Andrew.

mahgnia
26th Apr 2016, 09:29 PM
Gents,

I've got the winch up to an operational state.

It was used this weekend to haul 2 loads of about 400Kg each of firewood about 45m up a 3:1 slope. The winch pulled hard, without any labouring of the motor. The gearbox performed admirably, no apparent heating up, noise, or backlash increase after testing.

I've used some old Telstra rope for testing, and it was somewhat marginal for tensile strength under that load, but held up until it got chewed up in the drive gears...

The fuel tank mounting was a temporary affair. I didn't want to commit to the tank mountings until it was tested, as i had to do a repair on a split in the old tank with a soldering iron.

Some improvement and work is still needed:
1. I need to make up a hawse fairlead to prevent the rope running of the end off the drum when not properly aligned in the pull. (cause of the chewed up rope!)
2. Finalise the tank mounting and fuel line.
3. Install an on/off switch for the motor.
4. Clean up and paint over the ugly welding on the base frame.
5. Fit a gearbox output end yoke to take the output torque as I am a bit sceptical about the motor mounting bolts and crankcase taking the full torque (4 x M6 screws).

Pictures of the winch, with the direction selector, remote throttle handle, cobbled-up tank mounting, and old rope.
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Andrew.

mahgnia
1st May 2016, 12:32 AM
I've built and attached a hawse fairlead to the winch. Not tested yet.

10mm aluminium plate from a scrap aluminium right-angled stair structural part. Part of the 6mm web retained for stiffness.
Steel attachment plates.
Slot was machined with a 12mm end mill.
Radius on both sides machined using a 1/4" radius router bit with a 12mm guide bearing. Outside face radius used full 1/4" depth of router radius. Inside face radius depth enough to make a smooth transition for rope to drum.
Cleaned up with a file and emery strip.
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Andrew.