Etymology From Middle English tredel, from Old English tredel; equivalent to tread + -le.
1
A foot-operated pedal or lever that generates motion.
To the rear end of the shaft B, is attached a band wheel, to the periphery of which is attached a strap J, which descends to a treadle, to be operated by the foot, but which requires no description.1846, editorial staff, “NAIL SWEDGING MACHINE”, in Scientific American, series 1, Volume 2, Issue 13, page 97:
There is an inconspicuous treadle let into the floor and when you step on it an air-operated door-opening mechanism is automatically activated; [...].1960 March, G. Freeman Allen, “Europe's most luxurious express - the "Settebello"”, in Trains Illustrated, page 141:
2
A device actuated by wheels passing over it.
As a car enters the parking area the front wheels pass over a treadle, causing a timber barrier to lift and allow the motorist to drive in and park. No money is required at this stage. As the car passes over a second treadle, just beyond the entrance, the barrier falls again.1962 July, “Talking of Trains: Automatic car park at Harlow”, in Modern Railways, pages 11–12:
You can play with treadling a straight or point twill, treadle just Block A, treadle just Block B, or mix and match all the options.2026, Sydney Sogol, “Blue Morpho Runner”, in Handwoven, volume XLVII, number 1, page 51: