GOVERNORSSpeed Limits & RepairIf a Service Replacement Engine is used, check the topgoverned speed using a tachometer, with the engineoperating on a completely assembled mower, to be surethe blade tip speed will not exceed 19,000 feet perminute. If necessary, change the governor spring oradjust the top speed limit device, so the engine will notexceed the recommended speed, based on blade lengthas shown. See page 6 for adjustment procedure formechanical governor.If a governor spring must be replaced, consult theappropriate Illustrated Parts List. Choose the propergovernor spring by engine type number. AFTER A NEWGOVERNOR SPRING IS INSTALLED, CHECK ENGINETOP GOVERNED SPEED WITH AN ACCURATETACHOMETER.Run engine at half throttle to allow the engine to reachnormal operating temperature before measuring speedwith a tachometer. To account for tolerances, which maybe required by tachometer manufacturers, we suggestthat the top governed speed of the engine be adjusted atleast 200 R.P.M. lower than the maximum speedsshown.Since blade tip speed is a function of engine R.P.M.,lower tip speeds require lower engine speeds.The chart below lists various lengths of rotarylawnmower cutter blades, and the maximum bladerotational speeds, which will produce blade tip speeds of19, 000 feet per minute.BLADE MAXIMUMLENGTHROTATIONAL R.P.M.18"403219"382020"362921"345622"329923"315524"302425"290326"2791NOTE: For correct no load R.P.M. by model and type,see engine sales manual. Note column.MECHANICAL GOVERNORMODELS N, 6, 8 (CAST IRON)DisassemblyLoosen the two mounting screws to remove governorhousing. The cup can be pulled off the governor gearand the gear will slide off the shaft.See Fig. 4. To disassemble the governor crank, drivethe roll pin out at the end of the governor lever; removethe governor crank bushing. Then pull governor crankout of the housing.Fig. 4. Governor Housing and Gear AssemblyRe-AssemblyTo assemble the governor crank, bushing and lever tothe housing, push the governor crank, lever end first, intothe housing. Slip the bushing onto the shaft:; then threadthe bushing into the housing and tighten securely. Placethe lever on the shaft with the governor crank in theposition shown in Fig. 5. Place the governor gear onshaft in cylinder. Place gasket on governor housing;then assemble governor housing to the cylinder andtighten in place with two mounting screws.Fig. 5 - Install Crank and Lever2
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