Torque levers
#1
Hello,

at first let me show you, why i did not like tubes as drive line:
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Rubber ages over the time and became hard ...

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... and brittle.



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Silicone tubes are still not the real solution. They are crooked and for this they do not rotate true. If in addition still misused as torque lever too, the gearbox will forced to tilt forward and then afterward at every rotation and the tube is bended also alternating. Often the cause of mysterious noise and/or irregular running.
To make things worse, when on load the tube takes an S-like shape, causes by the strain to prevent the gear box from tilting over. Also a good deal of the motor's power is needed to felt the tube and at least dissipated into unwanted thermal energy.


One of the solutions is to replace the tubes by an articulated drive shaft with universal joints.
But there are provision to made to prevent the gar box from tilting over and catch up the resulting forces caused by the torque. This device is called torque lever.


In the course of time i created a number of very different torque levers. Some of the solutions i made over the time:

[Image: dsc01222rljld.jpg]
SP 0-6-0 with really tight fit under the boilershell. Grandt Line coupling. The front end has got a oblong hole, so the angle of the gearbox can be adjusted.
Sprung function of middle pair of drivers still present.




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Drill and tap.

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Brass stripe (recycled etching frame)

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Bend to shape. Here too the sprung function still present.




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Radical different-minded solution.




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Shaft guide. Some pieces of styrene front and aft adjust the gear box within a fraction of an millimeter. This is only possible when the gearbox is straight upright.




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Articulated lever with possibilties for adjustment. The articulation still enables sprung action.




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Still an articulated torque lever. Recycled etching frame too.




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Another torque lever. Here the articulation point is the rear fixing point of the lever. The bolt is counterd by an nut inside and the head is not press fit down.




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0.8mm brass wire bend in strange shape. Artiuculation is enabled by "loose" fit of rear fixing point, in real the screw it is countered.

I hope this give you a little help for your next project.
Cheers Lutz
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#2
North West Short Line probably makes a replacement for that item. <!-- m --><a class="postlink" href="http://www.nwsl.com/nwsl-online-catalog.html">http://www.nwsl.com/nwsl-online-catalog.html</a><!-- m -->
If you can't find it, they can be reached by email or phone.
Andy Jackson
Santa Fe Springs CA
ATSF/LAJ Ry Fan & Modeler
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#3
Andy,

the only case whee you can use a tube as mechanical transmission is this kind of an nose suspended drive:

[Image: dsc03686hqjz.jpg]
Here in this case the shaft of the motor and the input shaft of the gearbox does not shift each other. They are both aligned and will stay so permanently. The tube will not be bended. In extreme case you can take here an piece of brass tube.

But in all other cases where the shafts are not 100% aligned or moving independent and altering it's position to each other, you have to use universals.


The ability of rubber or silicone hoses or tubes to transmit mechanical rotation power is based on the strain the hose can apply to the surface of the shafts.
In other words a classical case of press fit. To transmit torque, beside the inner strain of the hose, a certain amount of surface is necessary. Each longer the shaft, each bigger it's diameter, the more is the surface. And the more torque and power can be transmitted.

In this case shown on the photo the lenght of both shafts are rather short. Too short, not enough surface and aged rubber. This caused slipping of the shafts within the hose. The hardened rubber tube at least was replaced by universals.
Cheers Lutz
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