Gates belt theroy questions

[Greg Woelki]

Originally Posted by InFlight

See page 182 in the Gates Power Drive Design manual. The standard pre-tensioning center distance should be in the .02 to .03 inch range for most HTD or GT3 belting sizes used in robotics.

Hell no, that is significantly overtensioned. If you take a closer look at that document you'll see that they aren't referring to pretensioning distances at all:

Since fixed center drives are not recommended, center distance allowances for a Gates PowerGrip® belt drive are necessary to assure that the belt can be installed with-out damage and then tensioned correctly. The standard installation allowance is the minimum decrease in center distance required to install a belt when flanged sprockets are removed from their shafts for belt installation. This is shown in the first column of Table 4. This table also lists the min-imum increase in center distance required to assure that a belt can be properly tensioned over its normal lifetime.

The table immediately below that you got the 0.02" and 0.03" numbers from refers to the minimum amount adjustability (think versablock) in c-c distances that they recommend so that the belt is easy to install and so that it can be tensioned as it stretches over time (as timing belts often do in industrial applications).

In FRC, however, fixed c-c distances work great because of the limited run-time of our robots, and are generally designed to be exact or a couple of thousandths large.