This article is part of a section of the RcTek site that is devoted to informing the model car owner about the various different aspects of two speed transmissions, which are an increasingly popular fitment on radio controlled model cars today, whether they are a standard fitment, or are fitted as an upgrade.
This article is about the effects that wear can have on the two speed clutch bell.
The clutch bell used on radio controlled model cars is normally made from aluminium and suffers wear which can lead to gear changing and/or disassembly problems.
This wear occurs in two places, where the shoes contact the clutch bell and around the bearing holes. It must be mentioned that these problems only occur after extended periods of running your model car and are not normally design faults.
Wear On The Inside Of The Clutch Bell
The relatively soft aluminium of the clutch bell wears away at a faster rate than the clutch shoes, which produces a lip on the inside of the clutch bell and makes it hard to disassemble the gearbox. This wear can also lead to problems with gear changes.
The image on the right shows a cross sectional view of the two speed transmission and the close up view on the left clearly shows the resultant wear. If there is a large amount of wear the best solution is to replace the clutch bell.
If the wear is not too great, the problem can be solved by the use of a file to remove the offending material. A sharp craft knife can also be effective in removing the metal lip, as long as the necessary safety precautions are observed.
Wear on the Clutch Bell Bearing Housings
Although remote controlled model car two speed transmission assemblies usually use flanged bearings, their increased contact area only serves to slow down any wearing away of the aluminium clutch bell. This wear happens for a number of reasons;
The bearings can bind up due to lack of lubrication or being contaminated by metal particles from the clutch bell.
Misalignment of the pinion and spur gears can put unequal loading on the transmission assembly, which leads to the bearings pressing on the clutch bell.
The animation on the left shows the affects of the wear that it is shown in the image on the right.
Not only does the clutch bell start to wobble from side to side, it can also start dragging on the clutch shoes, which can affect the performance of your model car.
The only solution in the case of severe wear is to replace the clutch bell.
Summary
You will now hopefully be better informed as to what kind of wear problems occur with the two speed transmission systems used on remote controlled model cars and the effects of such wear.
If you have any comments or suggestions about this or any of the other R/C car content on the RcTek site, please feel free to ask them on our On-line Forum
