The Model 750 DC Tachometer embodies a permanent magnet field surrounding a rotating armature. The commutator segments are made from a special non-corrosive alloy which has an exceptionally long life. The brushes are of a self-lubricating material and are carried in a self-aligning holder which equalizes the pressure of both brushes. The armature shaft rotates on ball bearings which under normal operation do not need lubrication for 15,000 hours running time or approximately 3 years, whichever comes first. Maximum recommended speed is 5,000 rpm. Brush life is greatest at the lower speeds.
Dust-proof aluminum alloy housing. S.A.E. 7/8" screw type steel mounting with 3/16" drive dog. Used on Diesel and gas engines where a standard S.A.E. screw type tachometer outlet is available. Two binding posts for electrical connection.
Approximate torque: 3.0 oz.-in. starting, 4.0 oz.-in. running (1000 RPM).
Type J2R: Same as Type J2, except internal resistance is 200W.
Type M2: Same as Type J2, except front bearing seal has been eliminated to reduce torque burden. Recommended for use with a low-torque gear box. Approximate torque: 1.0 oz.-in. starting, 1.0 oz.-in. running (1000 RPM).
Binding Post Cover Box: Provides protection for the terminals, and has a 1/2" NPT connection for conduit.
Replacement Brush Kit: Metallic leaf brushes are of an alloy which will wear before the commutator bars. Brush replacement is a simple field operation.