Here are some of the most common motors available for the Arriflex 16S and Arriflex 16M series of cameras:

The ARRI Variable Speed Motor (Cat. No. 1160) is probably the most common motor for the Arriflex 16S. From the ARRI catalog, "For 8 volt battery operation with built in rheostat for regulation of camera speed between 4 and 48 fps. It is specially designed to come up to speed quickly. A knurled disk situated behind the rheostat cap enables the motor to be switched to 'forward' or 'reverse'. A knurled knob behind this disk is for turning the camera mechanism by hand for loading and to place the mirror reflex shutter in viewing postion when camera is not running."
The ARRI Governor Controlled (Constant Speed) Motor (Cat. No. 1161 (24fps), 1162 (25fps)) is probably the second most common motor for the Arriflex 16S. From the ARRI catalog, "For 8 volt battery operation with fixed camera speed of 24 fps or 25 fps. This speed is automatically maintained and cannot be changed. The motor is designed for forward drive only, and a knurled knob for turning the camera mechanism by hand is also provided."
The ARRI Governor Controlled Motor with transistor (Cat. No. 339 301) is the latest version of the constant speed motor for the Arriflex 16S. From the ARRI catalog, "The Governor Controlled Motor is designed to operate from 8 volts, DC, at a fixed speed of 24 fps. (Speed tolerance, plus/minus 1.5%). The Governor Controlled Motor runs Forward only. It is perfect for Pilotone synchronous sound filming as well as all other applications where the camera is to run at sound speed."
The TOBIN Variable Speed Motor TM-23 is Clive Tobin's 12 volt variable speed motor made for the Arriflex 16S. When powered by twelve volts, it runs at speeds from 0 - 50 fps, forward and reverse. It can be run for short periods with 14~16 volts to obtain a high speed of 60 fps.
The TOBIN Crystal Sync TXM-22 is Clive Tobin's follow up to the TXM-17. This 12 volt DC motor can be set to run three 50 Hz HMI crystal speeds (20, 25, 50 fps) and six 60 Hz HMI crystal speeds (6, 12, 20, 24, 30, 40 fps). It will run all these crystal speeds in forward and reverse, as set by the recessed switch on the side of the motor. The red sync light on the back of the motor comes on when sync is lost. The motor can be controlled by Clive Tobin's TCS Milliframe Controller.
The TOBIN Crystal Sync TXM-22A is the final version of Clive Tobin's crystal sync motors for the Arriflex 16S. This 12 volt DC motor can be set to run three 50 Hz HMI crystal speeds (20, 25, 50 fps) and five 60 Hz HMI crystal speeds (12, 20, 24, 30, 40 fps). It will run all these crystal speeds in the forward direction only. The red sync light on the back of the motor comes on when sync is lost. The motor can be controlled by Clive Tobin's TCS Milliframe Controller.
The TOBIN Crystal Sync TXM-17 is Clive Tobin's first crystal sync motor that was all enclosed in one motor unit. This motor can be set to run seven 50 Hz HMI crystal speeds (10, 12.5, 16.67, 20, 25, 33.33, 50 fps) or seven 60 Hz HMI crystal speeds (12, 15, 20, 24, 30, 40, 60* fps) by setting the recessed switch on the side of the motor. This motor only runs in the forward direction, not in reverse. The red sync light on top of the motor comes on when sync is lost. The motor is powered by 12 volts DC (* It can be run for short periods with 14 volts DC to obtain the crystal speed of 60 fps). It can be controlled by Clive Tobin's TCS Milliframe Controller or Videoframe Controller.
The TOBIN Crystal Sync TXM10-S is one of Clive Tobin's first crystal sync motors made for the Arriflex 16S. It consists of a base unit that mounts under the camera and a separate motor unit that mounts in the motor socket on the camera. This motor can be set to run eight 50 Hz HMI crystal speeds (5, 10, 12.5, 16.67, 20, 25, 33.33, 50 fps) or eight 60 Hz HMI crystal speeds (6, 12, 15, 20, 24, 30, 40, 60 fps) forward and reverse. It's powered by 12~14 volts DC and is compatible with the TOBIN .001 FPS/step Milliframe Controller.
This ARRI Synchronous Motor is the original version of the synchronous motor for the Arriflex 16S. From the ARRI catalog, "The Synchronous Motor operates on 110-120 Volt, 60 cycle, single phase AC. Its speed is absolutely constant, regulated by the frequency of the alternating current, and unaffected by variations in the line voltage. Because of its speed accuracy, the Synchronous Motor is essential for lip-synchronized sound shooting. The power supply unit of the Synchronous Motor includes a step-down transformer-rectifier, which delivers 8 volts DC to the Torque Motor of the FIlm Magazine."
This ARRI Synchronous Motor (Cat. No. 339 302) is the second generation synchronous motor for the Arriflex 16S. From the ARRI catalog, "The ARRI 42 volt Synchronous Motor and Power Supply combination has several special advantages. The Power supply itself operates from regular 117 volt, 60 Hz, single phase power lines. It supplies stepped down voltage for the 42 volt motor. The same Power Supply also develops 8 volts DC for magazine take-up and the automatic clapstick."
This is the first generation ARRI Animation and Time Lapse mechanism for the Arriflex 16S. From the ARRI catalog, "The Animation Time Lapse Mechanism is inserted into the camera in place of a motor, and any of the three ARRI motors can in turn be inserted into the device. It makes one exposure per impulse. This can be given either manually (release button on the housing) or by remote control, supplied with the instrument, or by an intervalometer. There is also provision for connecting a remote frame counter. "
The ARRI Single Frame Mechanism (Cat. No. 1220) is a module for taking single frames with the Arriflex 16S. From the ARRI catalog, "A single frame mechanism is inserted between camera and motor. The device can be operated by means of a manual release or by means of an intervalometer. A 4-digit frame counter is built into the device. The single frame mechanism can be set to exposure times of 1/10, 3/10, and 9/10 of a second by changing some gears. "
The ARRI Single Frame Motor with Control Console (Cat. No. 339 337) is the latest version of the single frame motor for the Arriflex 16S. From the ARRI catalog, "The Single Frame Motor has every essential capability required for single frame operation. The Motor may be programmed so that one frame cycle is completed on a single pulse. Exposure times of 1/8, 1/4, or 1/2 second may be selected. The Motor may also be programmed to go through one-half cycle on one pulse, stopping with the camera shutter open, and to complete the cycle on a second pulse, stopping with the camera shutter closed again. This capability makes possible extended time exposures. Features include: Contacts for strobe flash synchronization; frame counter; forward and reverse operation; stop motion or continuous operation; remote control via a programmed intervalometer."