67700-1R is an analog DC tachometer generator designed for closed-loop speed feedback of Reliance classic SCR DC drive systems. Original production has been discontinued. Available market stock includes unused surplus original units and fully tested refurbished products for maintenance replacement on aging papermaking, metallurgical and chemical DC drive equipment. It shares unified mounting dimension with other variants of 67700 series for drop-in interchangeable installation.

67700 is the base part number of Reliance standard analog tach generator product line. Suffix 1R specifies customized internal winding specification and rated output parameter. Different suffix markings only adjust coil configuration and output voltage grade while keeping identical housing outline, flange dimension and drive shaft size.

Nominal rated rotating speed reaches 2500RPM with standard DC output voltage at rated speed. Internal armature winding resistance is controlled within factory tolerance range. Dielectric withstand voltage between internal coil and metal housing hits 1400VAC, and insulation resistance exceeds 1000 megaohms under regular ambient condition. Operating ambient temperature ranges from -20℃ to +70℃, storage temperature spans -40℃ to +85℃, and working relative humidity is limited between 5% and 95% under non-condensing environment. Designed mechanical service life is above 25000 working hours under rated running condition and conforms to UL industrial component standards.

The unit is constructed with fixed mounting flange and single-ended solid drive shaft for direct coupling with motor rear shaft extension. Two bare outgoing leads are reserved for hard wiring without plug-type connector. No digital bus communication interface is equipped, and all analog speed voltage signals are delivered to drive control board via discrete wiring.

It converts real-time motor rotating speed into proportional DC analog voltage signal and transmits feedback signal to Reliance SCR drive mainboard to fulfill closed-loop speed regulation. The drive will activate speed loss interlock protection and cut off main power output if tach signal breaks or opens circuit to prevent motor overspeed runaway.

It is widely paired with Reliance high-power DC motors for metallurgical rolling mill transmission, papermaking dryer cylinder drive and chemical large DC pump equipment, acting as critical spare part for overhaul and retrofitting of legacy analog DC drive control systems.

Cut off total equipment power supply and wait over 20 minutes for residual voltage release before disassembly or wiring modification. Finish annual maintenance by cleaning coupling dust with dry low-pressure compressed air and checking shaft abrasion and lead insulation aging. In case of unstable speed swing or speed feedback alarm without motor mechanical failure, test actual output voltage variation along with rotation speed prior to component replacement. Prevent sharp axial impact on drive shaft during installation to avoid internal armature deformation and permanent damage.