The Pike's Peak line (still open), to quote its own website, (www.cograilway.com) uses the Abt rack system - which is the same one that's used on Snowdon. This has a pair of milled rack rails in the centre of the track, out of step with each other, with which a pair of pinions on each driven or braked axle on the train engage. The pic Carnkie posted only seems to show a single rack, but this may well be because it's at a loop (only a single rack is used on the approach to pointwork).
The extra bits of angle iron either side of the rack rails on Snowdon aren't grippers as such (that's the Fell system), but serve as guides for extra bits hanging down from the train intended to prevent the pinion riding up and out of the rack, which was what caused the 1896 disaster. At the time, Dr Abt said he thought this was unnecessary, and laying the track properly was all that was needed. AFAIK no other Abt railway has ever felt the need to add these components.