Axle Hung Motor Gearbox (AHMG)

[cabbage]

The problem with the drawings as supplied by IanT are that they are a "Palimpsest" and has all the various wheels and gears etc all on the ONE drawing and nothing is dimensioned. Because looking at the drawing there does not appear to be any form of front fixing and the motor is thus secured by some form of clamp fitting like a Jubilee clip(?)

To collapse the drawing into a std triangular format I need to know specifications of the motor -in fact I don't even know what one looks like. Does it actually HAVE any front fixing bolts or screw holes? Where are the power  terminals -are they screw, solder, clamp or plug fittings?

The total length of the gear chain is 130mm. The physical volume of the finished design will be smaller -but the topological fact is the gear chain length will still remain 130mm regardless of how I move the axis points...

Now -would someone PLEASE supply a drawing / photo / and dimensional specs of this motor!!!!

On A Personal Note: I would be highly surprised if the 7 pole motor puts out more power than my "Std" 80p motor from RF Potts -let alone my £2 Johnson monsters from the same source. I know that Tim is going to test the 7 pole on the East Midlands Group stand at the AGM. I hereby offer one of my stock of SME and Johnson motors for him to evaluate at the AGM.

regards

ralph

[IanT]

The motor dimensions were given earlier in the thread Ralph - but here they are again.

HQ7P motor dimensions (rounded up to nearest 0.5mm) are as follows:

Main body  - Length = 50mm ; Diameter = 29mm
Front Boss - Depth = 3mm ; Diameter = 17mm
Rear Boss -  Depth = 3mm ; Diameter = 12mm
Shaft  -  Length = 20.5mm (from face of front boss); Diameter = 4mm

Note - electrical connections are on both sides of the rear boss 18mm apart - and will need clearance/access.

By the way - no manuscripts have been harmed in the making of my doodles!   

Regards,

IanT

[cabbage]

IanT,

Are there ANY mounting holes on the front of the motor? If so what Radial / Angular  Distance and Size are they? I have a feeling that there MUST be to control the reaction torque from the magnets in the casing? If anyone can supply three shots (front side and rear) of the motor it would help a great deal.

Looking at the specs above it would seem that 3mm plate would be the perfect motor face and 2mm for the rear -but how the motor would bolt to to it is as yet unknown. There will have to be an insulating mount at the rear of the motor to hold the rear bush and allow connection. A slice of Derin or preferably Nylon -not PTFE(!) should provide this. The Gears 2 and 3, I would bolt together with three M4 bolts, I would also take the time to tap the holes in Gear 2 to M4. There would have to be a "take up" spacer between the two gears, (this would probably be an M4 nut and couple of washers). I would glue the Gear 3 to the Gear 2. Not that I would use it to transfer torque, (that is what the M4 bolts are for), but to act as a "wave termination ring" and clamp down on vibration. I would also do the same three M4 bolts with spacers for the Gear 4 but given the dampening mass of the wheels and axle the wave termination ring effect of this -it might be a case of "Guilding the Lily"...

In the design begun above ONLY Gear 1 is clamped to the shaft. I would imagine that the shaft is some form of hardened steel (for the sake of thinking and calculation I will imagine that it is 4mm Silver Steel). Ideally we need two points of clamping. It would not be too hard with the brass hub on the nylon gear to machine and tap through to give a grub screw on either side -using the steel gear it would be even easier. Thus one side of the boss would have a cup ended M4 grub and the other side a pointed M3 grub screw. I would fix the M4 first -then the M3.

I have opted to use mild steel 8mm bar for the axle shaft to the wheels, and 2mm+3mm BMS as this is cheap and easy to machine and tap.

I await pictures of my victim!!!

regards

ralph

[IanT]

Not on mine Ralph - although the same motor (as used in the Sentinel gearbox) has had two tapped mounting holes drilled in the front boss to mount it to the gearbox. So that is possible.

There were quite a few things I could have done when setting out to build this unit but since one of the objectives was to try and not have to modify anything (or at least minimise that need) I was looking for alternatives. The same logic applied with pinning gears to axles etc.

Regards,

IanT 

[cabbage]

IanT,

So, what you are saying is that the motor devolves to three discs -one of 17mm dia and 3mm thick backed with a disc 29mm dia and 50 thick and finally a disc of 12mm dia and 3mm thick?

The only method of restraint is circumferal clamping? But drilling and tapping the front of the boss is possible? Could it take M3 or M2.5 -probably not(?) The best method (sorry Phil) is probably to STICK the motor to the motor plate. A 2 hour epoxy should have more than sufficient strength for the job.

OK -time to go away and munch on a few ginger nuts and sup some tea whilst I play!!!

regards

ralph

[IanT]

Correct Ralph   

And you may be right about the potential use of expoxy for a motor mount too. Don't know, I haven't tried it - but it's an interesting thought.

Regards,

IanT

[cabbage]

OK -here it is! I am sorry for the delay -but I have had to "motivate" my Son and his homework....



It is presented as a right angled triangle -if you want YOU can do the calculations for other triangles! The axle for Gears 2 + 3 is an M4 threaded bar which acts as spacer. How you re-enforce the parts of the plates is up to you -even blocks of wood glued into the spaces would work well. I would suggest that an 8mm bore tube form the axle connecting piece 3mm BMS can be tapped to provide screw holes and stud sets.

There is plenty of spare "meat" on the plate to attach brackets springs galore -you may rotate and malign as you see fit. If you reverse the positions of gear 2, 3 and 4 then the over hang of the motor will not be so great -but it dos make the connections harder.

It presented to you under GPL 2.0 -enjoy!

regards

ralph

[cabbage]

Robert has quite correctly pointed out that the Buchli drive would also work! I do have some "test" doodles on a working version and if you likeI can present a "working drawing" here. The Buchli drive requires some "mind scrunching" to understand how it works but it a rotary version of the power transmission via levers as espoused by Hagans.

The forces are passed by 2 long rods to 2 small short levers that are meshed at the connecting point. The whole thing is toplogicallt RIGID -it moves as it rotates!

regards

ralph

[Peaky 556]

Ralph,
Ignoring the Buchli Drive "flight of fancy" and keeping my wheels firmly on the rails, a question please on Gear 2 in particular from your design...

As this is very large in diameter and will come down close to rail head level, it could be very visually obtrusive. Is the gear a solid disc, does it have spokes, or if not, could the bulk of it be machined away to give a spoked appearance and thereby disguise its bulk?

Another question is the colour? Red or white might be difficult to disguise...

Thanks, Tim

[cabbage]

Tim,

The Gears 1, 2 and 3 are  here:

http://www.technobotsonline.com/mod-1-plastic-spur-gears-brass-hub.html

They are solid discs. The bulk of Gear 2 will sit inside the bogie frames. The unit can rotate on the 8mm tube to give more clearance from Gear 2 to the rail if requires. At MOD1 48T, Gear 4 is the correct size not to touch the rail head -if using a 3 feet 7 inch wheel (48.3mm scale).

regards

ralph

[classicdelights]

Tim et all

I have today ordered the laser cut parts for Ian's design and also the materials including the bearings and the gears from Muffett.  In accordance with Andrew's very good advice I have specified a mix of steel and brass gears, the smaller being steel.  I anticipate having a couple of units put together shortly and we will then be able to see how it looks, works and more importantly costs.  I asked Muffett about discount as the gears are not cheap and we could have 5% if more than 10 sets are ordered so not much of a saving but something.

I will keep you all posted.  Perhaps we will have two different gearboxes to see at the AGM!

Phil

[cabbage]

You will.

With the exception of the specified gears everything is available from my "bits boxes". As I don't actually own one of these expensive motors -could I borrow one of yours Tim?

ralph

[cabbage]

All gears Nylon and Delrin  ordered (total cost -£4.08p excluding 1st class post). Next step -the plates... I DO have some 3mm thick Whale grade Paxolin that would do the job. But I suppose as they would be a structural plastic - they would not count in your eyes -so I will dig around for some steel plate.

I have, if you look elsewhere on this forum, built a G3 loco, (A Swiss C+C Krokodil) -for under £200. I am "quietly confident" about being able to bring in the gearbox at under £10.

ralph

[John Candy]

As I don't actually own one of these expensive motors -could I borrow one of yours Tim?

Ralph,
I have spares and will send you one (which you can keep).

Regards,
John.

[cabbage]

Thank you for the offer John -But I would prefer it to be a LOAN! You may have your motor back at the end of the AGM. The demo gearbox will be a "proof of budget" example. It will used to show that a cheap and simple gearbox can be made with just hand tools for under a tenner. This does of course mean that a C0-C0 would cost £60 + motors. I expect people to try and test the gearbox to destruction at the AGM to satisfy themselves that the concept and the design are both valid.

At the insistence of my son -the plates will be made of 6mm Polycarbonate. Lighter than steel and transparent to see things go around...

regards

ralph