Built-in Gear Train for Multi-Turn Application
Various resolver models from AVG Automation are available with a built-in precision gear train.  The resolver makes one turn for many turns of the input shaft.

Explosion-Proof
AVG Automation's series E8R resolver meets the requirements as per Division 1, Class 1, Groups B, C, and D with appropriate autotech PLS

Dual-Resolvers for Multi-Turn Application
A multi-turn resolver consists of two resolvers coupled to each other through a gear train.  One of the resolvers, called the fine resolver, is coupled to the machine shaft in such a way that it turns at the same rpm as the machine, while the other resolver, called the coarse resolver, is geared down by the gear ratio used.  As the shaft of the multi-turn resolver turns with the machine movement, the coarse resolver keeps track of the number of revolutions and the fine resolver keeps track of the shaft position in each revolution.  Thus, the combination of the two resolver-signals gives the absolute machine position.  The great train uses an antibacklash gear to eliminate backlash errors.