Cage Gears

[OldMcDonald]

I am considering a modification to a home made seed drill that currently has the seed plates mounted vertically on a drive shaft and they are cut into small seed boxes, supplied by a larger hopper above, to pick up seed. I sow a wide range of seeds from vetch through to large fava beans and the current system is not satisfactory for all sizes.

I want to change the drive from rotational forward through a gearing to horizontal - exactly the same as a pair of bevel gears would. The seed plates (to be made in diffetrent sizes) would sit horizontally in the bottom of the seed box and drop the seeds through a hole in the base of the box and into the feeder tubes for the sowing tines. There is very little force needed to turn the shaft and I wondered whether I could use cage gears I make myself. Any comments greatly appreciated.

 

[bcp]

Cage gears would be fun to try.



How about using a couple of the small bevel gears from inside an automotive differential?

Bruce

 

[Willl]

1 to 1 ?, how bout some of those 90 degree drill motor adapters ?

 

[OldMcDonald]

I am in inland Portugal. That probably means absolutely nothing to members of TBN, but, the bits and pieces you blokes in the US take for granted are simply not available. In other parts of the world where I have farmed - England, Australia, Scotland for example, I would simply go out and buy the bevel gears I need. I cannot do that. The cost of importing is prohibitive. I make my own or go without.

The photo from bcp is sort of what I had in mind. I believe that the tolerance on fitting the two gears together is a lot more than with bevels and I see no reason why I cannot make such a set-up in metal, but I know there is so much knowledge on this site that I decided to seek some comment.

 

[Willl]

That is so messed up, is there anything I could take apart and send as 'parts' ?

 

[OldMcDonald]

Willl, Extremely kind of you, but it will be no great hardship to make some sets of cage gears. The present drill is mainly for corn and only has two rows, so two sets of gears are all that is needed to try out the idea. There is heavy import duty on anything coming in, and the stories I have heard suggest the amount is not relevant to the value of the imported goods. There is great satisfaction in completing something different that is cheap, effective, even if not as good as mainstream manufactured equipment, and readily repairable.

If the system works (and I see no reason why not) then it could be applied to anything where the force is low and a change of direction is required. I had in mind using half-inch rods for the "spokes". I can turn the delivery on the present set up with one finger when it is raised on the tpl. The drive from spider wheels to the present seed plates is via bicycle cogs and chain. It is set for 1:1 but could be changed with different bicycle sprockets. There is no slip on the spider wheel drivers and forward speed does not alter the number of seeds delivered - only the seed plates do that and I was intending making interchangeable plates along the lines of the Earthway garden seeder to suit the different seed sizes. The spider wheels are one metre diameter so pi times the 1m gives me the ground coverage per sowing tine. I then use the spacing between seeds needed to work out how many to drop per revolution. I have had limited success with altering the seed level in the small seed boxes, and the size of the opening through which the seeds flow to the delivery tubes- round seeds are easier to work with than flat ones like fava beans. I just thought I could improve on my present system.

 

[BHD]

I have seen variable speed friction drives that are similar to the Cage gears, but they use a small rubber tire on a steel plate, one may have to put some thing like expanded metal on the plate for better grip, by adjusting the tire in close to the center or put near the edge one has variable speed, and if you use a small air tire one can adjusts the pressure of the mating surfaces by air pressure,

image from, Ten Variable-Speed Friction Drives | Mechanical Prasad

an intresting use, http://blog.hemmings.com/index.php/2013/03/14/smooth-going-with-friction-drive/
it was used as a car transmission

some lawn mowers and snow blowers us this type of drive for the transmission,

 

[OldMcDonald]

BHD, Thanks for the links. A very interesting possibility, but I would prefer not to have to go through the experimental stage of calculating the amount of slippage. I can imagine this slippage becoming worse over a few acres of use - needing a re-calibration. Additionally I would not be looking for changes of speed, but instead simply change the seed delivery plate inside the seed box.

 

[BHD]

another possiblity is a right angle belt drive, Law Of Belting, Power Transmission By Belts, Assignment Help
or 507 Mechanical Movements, 3, Pulleys with Right Angle Guides

 

[Mace Canute]

The side gears in a vehicle differential might work, just find a scrapped vehicle and salvage them.

 

[OldMcDonald]

Thanks guys, but the more I think about this the more I want to use the old cage and crown drive. Belts and pulleys need to be bought. Vehicle diff gears were the first thing I considered, but need to be found and then removed. Not so easy where I live. The time and cost involved in sourcing either would be better spent making what I need at a cost of time only - and time on the farm is a lot more valuable than time off the farm. No disrespect to everybody, but when I am here I can keep an eye on what is going on, often allowing the animals to graze nearby on odd patches of ground where they need to be "supervised". I suppose my lifestyle is alien to a lot of people around the world and I do not expect them to understand it. I am a peasant. An educated peasant, but still a peasant, who likes the simple things in life - good food, wine and a lot of rest time. I am happy to make what I need, I just thought that some folks on TBN would already have done it and had some suggestions.

 

[sparc]

If you want to experiment check out this website for a gear calculator.

www.woodgears.ca

But be prepared, if you go there you might not get out for a couple hours.
Very interesting site.
Check out the marble mazes too.

 

[OldMcDonald]

Thanks sparc. I already knew about that one. It does seem that cage gears are more commonly made out of wood than metal, although I have heard that at least one US manufacturer of seed drills did you use them. I have not had a chance to search yet.

 

[sparc]

Yes, his gears are in wood but I was thinking it would be worthwhile to try out different gear ratios and diameters to get just what you wanted then you can create templates you can use to layout your gears on wood or metal. For a cage its pretty simple, not like cutting a toothed gear, but still helpful.

 

[OldMcDonald]

sparc, I agree with you. I work with someone else on these things and he is far more technical than me (actually makes his living from graphic designing via computers) and he led me to the site. Unfortunately he is presently on an assignment in London and I am not inclined to bother him unless necessary. He knows what I am planning to achieve though and I am running with the notion of a cage gear in metal at this stage. I am almost at the experimental stage, but not quite. Time is always short, but especially in springtime.