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By Michelle O'Brien
Standard Meccano chain and sprocket drives have a nasty habit of jumping a link or two now and again, or so I've found. If you can't/don't get the positioning of the two sprockets quite right, especially where one is above the other (rather than them being aligned side by side), and if/or the chain linking them is a shade too slack — instead of a nice smooth drive you sometimes get a series of jerks as the chain links jump the sprocket wheel teeth. It mostly happens under heavier loads.
MFA/Como Drills have a range of timing pulleys and belts which can overcome this problem for situations where smoothness and precision of drive transmission are essential — for example, if you're driving something using a stepper motor that needs exact positioning with no slippage. The pulleys are Meccano-compatible with grub-screw fastened hubs that fit snugly on standard 4mm Meccano axles. They come in a variety of sizes from 16 to 44 teeth and the driving belts for them range in circumference from 165mm to 840mm.
MFA/Como Drills timing pulleys
MFA/Como Drills timing belts
The price you pay for absolutely positive transmission is that the pulleys are a bit "chunky" by Meccano standards, which can be a difficulty where space is tight. But of necessity they have to be a fair bit wider than "slim-line" Meccano sprocket wheels in order to accommodate the 9.8mm width of the timing belts that ensure the no-slip drive precision.
For full details of the range go to www.mfacomodrills.com/timing_belts_timing_pulleys/timing.html
» This article appeared in the September 2012 issue of SELMEC News.