Murphy OS-77R-I User's Manual
Contents
1. LOWER RPM NOTE Relay contacts are between terminals 2 and 5 WIRING INSTRUCTIONS BATTERY SPECIFY VOLTAGE TO gt STARTER HOLD IN RACK PULLER JE WARRANTY OS77R USED WITH AN ENERGIZED TO RUN ETR SOLENOID Note For distributor ignition applications you may use a Model OS77R I Simply con nect terminal three 3 to the negative side of the ignition coil You will not need a mag netic pickup with the Model OS77R 1 OS77R USED TO SHUT DOWN A MAGNETO IGNITION ENGINE Note Battery power must be available Also note a Murphy Model 169 PH magnetic switch is used in place of a Model 117 A two year limited warranty on materials and workmanship is provided with this Murphy product Details are available on request and are packed with each unit2. Model OS 77R Model OS 77R I OS77R OS PM5 EFFECTIVE 12 93 Smurphiy Overspeed Speed Switch With Relay Output GENERAL INFORMATION AND MOUNTING DIRECTIONS LD LD E EEJ WARNING A Z WARNING Y BEFORE BEGINNING INSTALLATION OF THIS MURPHY PRODUCT Disconnect all electrical power to the machine Make sure the machine cannot operate during installation Follow all safety warnings of the machine manufacturer Read and follow all installation instructions Installation Accessories Hardware tools and optional equipment needed to in stall the model OS77R E Tools as needed for the system mounting such as drill and screw driver E 18 ga wire for extension and hook up E Set of wire terminating tools E Wire termination such as ring or spade terminals DESCRIPTION The OS77R is an Overspeed Shutdown Switch used for protecting the engine from excessive operating speeds The unit monitors a frequency generated from a magnetic pickup The OS77R I functions identically to the OS77R but monitors engine speed from a distributor ignition If the unit senses an engine speed higher than the ad justable set point the unit will cause the engine to shut down WARNING Perform the mounting operation with power source off The OS77R module is de signed to be mounted in a flat panel First drill the mounting holes as shown on the template included with the packing Insert the module from the back side of the panel and in
3. stall mounting hardware SETTING THE MODEL OS77R SERIES IMPORTANT The the following instructions as sume terminal number 5 is grounded Please refer to wiring and mounting information before attempting to ad just the unit These steps must be done before the fine tuning can be accomplished The following steps should be followed for first time setup of unit A Turn OVERSPEED ADJ fully clockwise B Remove the wire from terminal 2 of the OS77R C Start engine and run at the highest RPM desired This is the RPM at which the engine should be shut down if exceeded D Connect a Voltmeter or test light between Termi nal 1 positive and Terminal 2 negative of the OS77R You should read no voltage test lamp will be OFF E Slowly turn OVERSPEED ADJ counter clockwise and STOP the INSTANT battery voltage is indi cated on the voltmeter or the test light comes ON F Slowly turn OVERSPEED ADJ clockwise about 1 8 of an inch Now tighten the locknut on the OVERSPEED ADJ without disturbing the setting G Re connect the wire to Terminal 2 on the OS77R This reconnects the OVERSPEED shutdown cir cuitry NOTE If further adjustment is needed Turning the OVERSPEED ADJ clockwise RAISES the shutdown point This allows the en gine to run at a HIGHER RPM Turning the OVERSPEED ADJ counter clock wise LOWERS the shutdown point This will shut down the engine at a
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