816230 Mercruiser RETAINER

The gearbox has two output gears driven by a single input gear or pinion, all of which are straddle mounted between ball bearings. Power is transmitted from the engine to the pinion by an input shaft that is splined to mate with the pinion on one end and keyed to mate with a sheave and bushing on the other end. The sheave is belt driven by a sheave at the back of the engine. The engine sheave is bolted to the engine power take-off and the power take-off is bolted to the engine flywheel housing.Lubrication
The oil level in the gearbox should be kept at the proper level in the sight gauge to ensure proper lubrication of internal components.Under normal operating conditions the SAE 90 gear lubricant (GL) specified under "Service Data" should be used; however, the lubricant should be changed if the operating temperatures are higher or lower than normal: 1. If the gearbox case temperature is consistently above 220 degrees Fahrenheit (104 degrees Celsius), use an oil with a viscosity of SAE 140.2. If the atmospheric temperature is 30 degrees Fahrenheit (-1.1 degrees Celsius) and above, use an oil with a viscosity of SAE 90.3. If the atmospheric temperature is 50 degrees Fahrenheit (9.9 degrees Celsius) and below, use an oil with a viscosity of SAE 30.Internal and external splines should be liberally greased whenever the hydraulic pump is replaced.Removing The Gearbox
STARTING OF THE ENGINE CAN CAUSE INJURIES TO ANYONE WORKING ON THE PUMP DRIVE GEARBOX. SHUT THE ENGINE DOWN, TAG THE ENGINE CONTROL AND LOCK THE MAIN BATTERY SWITCH AT "OFF" BEFORE REMOVING THE GEARBOX.
1. Close the pump suction shutoff valve. 2. Unbolt and remove the engine turbo cover assembly.3. Attach a lifting device to the air cleaner mount. Disconnect the 90 degree elbows from the engine and unbolt the throttle cable clamp from the mount. Unbolt the air cleaner mount and lift the air cleaners, mount and intake ducting away. Cover all openings.4. Remove the drive line cover. Loosen the jam nut and turn the adjusting nut to relieve the pump drive gearbox drive belt tension. Slip the belt band off the gearbox sheave. 5. Mark all the hoses connected to the hydraulic pumps for identification when installing the pumps, thoroughly clean around the connections, then disconnect the hoses from the pumps. Cap or plug all openings immediately. 6. Support the track drive and control (auxiliary) pumps, about 120 pounds (54.5 kg) total, remove the track pump mounting bolts, pull the pumps straight back from the gearbox until the track pump shaft is free, then move the pumps away. Cover the opening in the gearbox. 7. Support the conveyor pump, about 26 pounds (11.8 kg), remove the pump mounting bolts, pull the pump straight back from the gearbox until the shaft is free, then move the pump away. Cover the opening in the gearbox. 8. Remove the drain plug and allow the lubricant to drain from the gearbox.9. Remove the sight gauge and fittings from the gearbox.10. Attach fabricated lifting lugs to the gearbox.11. Attach a lifting beam and lifting device to the lifting lugs and support the weight of the gearbox, about 150 pounds (68 kg).12. Remove the gearbox mounting bolts from the gearbox support.13. Lift the gearbox straight up until the gearbox is clear of the mainframe, then move the gearbox away.PR-750B Two Pump Drive Gearbox Assembly Disassembling The Gearbox
1. Remove the bolts from the bushing in the gearbox sheave and replace them in the tapped holes. Turn the bolts alternately and evenly until the bushing is free of the shaft, then remove the sheave.2. Unbolt the input adaptor from the gearbox, then pull the input adaptor, shaft and bearings from the gearbox. If desired, remove the snap rings and bearings from the input shaft and remove the input shaft and seal from the adaptor.3. Remove the shaft adaptors from the gearbox, if still installed. Mark the shaft adaptors for identification during reassembly.4. Unbolt and remove the remaining adaptor plates.5. Pull the gear-and-bearing assemblies from the gearbox.6. Pull the pinion-and-bearing assembly from the gearbox.7. Pull the bearings off the gear shafts.8. Inspect the case for cracks or other damage, especially around the bolt holes and shoulders that support bearings.9. Clean and inspect the gears and shafts for chipped, broken or cracked teeth or splines.10. Clean and inspect the bearings.Assembling The Gearbox
Reassemble in reverse order of disassembly, placing the gear-and-bearing sub-assemblies first in the housing. Guide the adaptor plates over the exposed bearings and tap the plate or housing sharply to ensure that the bearings have moved into the bores completely. Install a new input shaft seal. Turn the input shaft by hand to ensure that the unit is free running. (Any binding of bearings in housing bores will load the bearings endwise and cause excessive heat when running).Installing The Gearbox
1. If necessary, position the sheave and bushing on the input shaft and install the bolts through the untapped holes in the bushing. Tighten the bolts to 112 ft.-lbs. (153 Nm).2. Attach a lifting device to the gearbox, the gearbox weighs approximately 150 pounds (68 kg). Move the gearbox into position on the support, then install the mounting bolts.3. Slide the gearbox belt band over the sheaves and adjust the belt band tension (see page 2.0-25). 4. Grease the shaft adaptors and install them in the appropriate gear hubs.6. Coat the conveyor pump shaft with noncorrosive grease, position the O-ring on the pump, insert the shaft into the gearbox and install the mounting bolts.7. Coat the track pump shaft with noncorrosive grease, position the O-ring on the pump, insert the shaft into the gearbox and install the mounting bolts. 8. Thoroughly clean around the pump fittings and hose ends, then connect the hydraulic hoses to the pumps. 9. Open the pump suction shutoff valve. 10. Loosen the suction line on the track pump until air-free hydraulic oil flows from the connection, then tighten the connection. Repeat this procedure for the control (auxiliary) pump and