Compact 2-speed gearbox.

[doug72]

For a MOC (WIP) I am currently attempting to build I required a 2 speed gear box to allow for the caterpiller tracks to run either fast or slow.
Fast when traveling to & from work site. Slow when working.
I have developed a compact gearbox with two axles using the old style driving ring to select the required gear as seen in images.

Top View:
IMG_4139 by Doug Ridgway, on Flickr

Underside view:
IMG_4140 by Doug Ridgway, on Flickr

To achieve this a white clutch (more correctly termed a slip gear) was modified to become a true 24T clutch gear, I belive this was once proposed for a modification to the Front Loader set 8265 but unable to locate this on old forum postings.

IMG_4138 by Doug Ridgway, on Flickr

The internals of the white 24T gear are removed and replace by an 16T grey clutch gear - push fit is adequate without need to glue in place.
Result a 2-speed gearbox that takes up very little space.

 

Edited October 20, 2016 by Doug72
replaced duplicate image

[Didumos69]

Indeed a very compact 2-speed switch. Can the center-part of the slip gear be removed easily? I don't have that part at hand.

[doug72]

13 minutes ago, Didumos69 said:

 Can the center-part of the slip gear be removed easily?

Yes they are quite easy to modify:
1/. Place 24T white gear with the side that has 4 small locating slots with tabs face up and support the gear teeth rim with 1L thick beams at several places on a hard surface.
2/. Using a 6mm diam. steel rod place over the centre grey axle bush and with a sharp tap with a hammer knock out the internals.
Discard the white part with grey bush and 2 small thin steel plates
3/. From the remaing 24T white gear part remove the 4 tabs - they snap off easilly.
4/. Insert a grey 16T clutch gear making sure the boss on back of the gear goes through the hole to slightly stick proud ( about 0.5mm)
You may need to enlarge the hole very slightly to allow the boss of the 16T clutch gear to pass through.
5/. No need to glue in as friction is usually enough to stop any slippage between the two parts.
 

[Erik Leppen]

Do I understand correctly that you modified a piece to build something that the Go Kart 42048 shows is perfectly possible in almost the same space without modifications?

[doug72]

15 hours ago, Erik Leppen said:

Do I understand correctly that you modified a piece to build something that the Go Kart 42048 shows is perfectly possible in almost the same space without modifications?

Yep. Because my version only requires 2 axles and 4 gears as against 3 axles and 7 gears for the Go-kart version.

Mine was built as a module using 7 x 5 frames for easy attachment into MOC but could be installed between two beams 7L apart with c/o lever.

For my MOC I may need another 2-speed unit so may try the go kart version.

The mod of the 24T clutch gear is not my idea it has been used in the past I believe for a modification for the Front Loader 8265

A Lego version would be a desirable addiion the Technic gears.

Edited October 21, 2016 by Doug72

[agrof]

13 hours ago, Doug72 said:

A Lego version would be a desirable addiion the Technic gears.

Great idea, definitely would be a useful new option.

[Jurss]

If You are purist, You could put some normal 24T gear inline with that 16T clutch gear. It seems, that there is place.

If You are purist, You could put some normal 24T gear inline with that 16T clutch gear. It seems, that there is place.

 

http://taranvh.com/2014/08/02/3d-printing-custom-lego-pieces/?preview=true

[doug72]

1 hour ago, Jurss said:

If You are purist, You could put some normal 24T gear inline with that 16T clutch gear. It seems, that there is place.

Don't see how you propose coupling a 16T clutch gear to the 24T gear to drive together !

3D printing expensive and as I have lots of spare white 24T clutch (slip) gears it is a cost effective & simple solution.

[Attika]

Great idea, thanks for sharing