R.A. Lee, The Knibb Family Clockmakers, Byfleet, 1664, pls. 89, 130, 131 & 134.
Joseph Knibb, 1640-1711, like Tompion and other 'great' clockmakers, made clocks of consistently high quality and diversity. Knibb experimented, more than any other clockmaker, with different methods of striking. In all he made eight different types from plain hour strike to the more obscure Roman strike and double-double six-hour strike.
The present clock probably originally used grande sonnerie strike where each quarter is struck followed by the preceeding hour and at the hour the four quarters are struck followed by that hour. It required the use of two calibrated countwheels mounted on either side of the backplate; on the left side was the small quarter wheel and on the right the larger hour wheel with 48 slots cut in it. A lifting detent spanned the backplate which pivotted in the centre and was tripped four times an hour by the quarter wheel.
The split front plate was another feature that Knibb used with his three train clocks. It was a feature thought to have originated from Ahasuerus Fromanteel and in fact many of Knibb's quirky features, particularly in his early clocks, stemmed from Fromanteel's original genius. Knibb clocks have unusually thin plates and consequently excessive wear is often evident and it also makes split plates more difficult to make and still maintain sensible rigidity, but on the plus side less friction is caused in the pivot holes giving greater accuracy. The split plates enabled the clockmaker to work on the three trains independently without having to disassemble the entire movement; a luxury that has earned the gratitude of many clock restorers over the centuries.