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7  - 

PRM125

 

Input Shaft: 

28.5mm diameter with 10 tooth spline to DIN5464. 
 

Propeller thrust: 

Ahead and astern thrust is carried by output shaft bearings of ample capacity for the approved rating. 
 

Output Flange: 

102mm diameter, with 4 holes 10.5mm diameter on 82.5 pitch circle diameter. 
 

Installation angle: 

The maximum fore and aft installation angle at rest is 15°. 
 
 
 

2. INTRODUCTION 

Prior to installationThe PRM125D read and fllow the instructions within this manual. Failure to do so will make the 
warranty void. PRM will not be responsible for poor installation,

 

wrong handling or defficient maintainence. It is it is the 

responsibility of users to install

 

guards and safety devices within maybe required by Health and Safety directives within 

different countries.

 

 
PRM Newage Limited. PRM125D marine transmission is a simple, lightweight, mechanically operated Gearbox for use 
in pleasure craft. Ahead and astern is selected by engaging a Cone Clutch which requires no adjustment. The 
PRM125D can only be installed onto engines that 

rotate left hand (anti-clockwise)

 as viewed when standing behind 

the Gearbox Output Coupling facing towards the engine flywheel. 
 

 

3. CONSTRUCTION 

 

3.1 Gearcase 

 
The Gearcase is made from heavy duty Aluminium Alloy rigidly designed and externally ribbed for efficient heat 
dissipation. The case assembly comprises two halves vertically split to facilitate servicing. 
 

3.2 Gear train 

 
The helical Gear train is manufactured from high grade Steel with all Gears being case hardened for long life. All Shafts 
are supported on Taper Roller Bearings which are amply proportioned to absorb all the thrust from the Propeller. 
 

 

4. OPERATION 

 

4.1 Output Rotations 

 
With the Control Lever in the mid, or neutral position no power is transmitted to the Propeller as the Cone Clutch is not 
engaged with either ahead or astern gears. Moving the Lever forward i.e. towards the Engine selects ahead, and 
rearwards i.e. towards the Propeller selects astern. In ahead the Output Shaft rotates in the opposite direction to the 
Input Shaft (which rotates as Engine). It is therefore necessary to fit a right hand Propeller. 
 

4.2 Lubrication 

 
All lubrication is supplied by internal splash with oil cooling being by radiation through the Gearbox case. 
 

4.3 Approved oils and oil filling 

 

The Gearbox is supplied direct to the distributor/ coustomer without oil and therefore prior to start up it must be filled 
with oil. Unscrew the Oil Level Plug located on the side of the Gearbox. Unscrew the Oil Filling Plug located on the top 
of the Gearbox. Fill the Gearbox with ATF DEXTRON II, III, or IV to GM specification or engineering approved equvalent 
until oil starts draining from the Level Hole. Refit the Oil Level Plug. Check the oil on the Dipstick. Refit the Oil Filller 
Plug. The oil is approximately 0.2 litres. 

 

 

CAUTION:

 Do not mix different brands, types or grade of oil.  

DO NOT OVERFILL THE GEARBOX AS THIS AFFECTS THE GEARBOX PERFORMENCE. 

 

 

Summary of Contents for PRM125D

Page 1: ...PRM125D WORKSHOP MANUAL...

Page 2: ...and therefore reserves the right to change specifications without prior notification Whilst every effort is made to ensure complete accuracy of the information in this manual no liabilities for inaccu...

Page 3: ...d oils and oil filling 7 5 INSTALLATION 8 5 1 General 8 5 2 Checking the engine Flywheel Housing 8 5 3 Checking the Engine Flywheel 8 5 4 Mounting the Gearbox to the Engine 10 5 5 Alignment to Propell...

Page 4: ...8 Gearcase 14 9 7 Re assembly of gearbox 14 9 7 1 Input Shaft 14 9 7 2 Output Shaft see 9 7 5 for shimming procedure 14 9 7 3 Idler Shaft 15 9 7 4 Selector housing assembly 15 9 7 5 Shimming 15 9 7 6...

Page 5: ...e Ltd direct quoting the serial number CLAIMS UNDER WARRANTY Claims for replacement of parts under warranty must always be submitted with the Gearbox serial number to the distributor who supplied the...

Page 6: ...erial number and should always be quoted when ordering spare parts the lower line is the Gearbox specification in the example given this translates as follows 125 D 2 First 2 digits Gearbox Model 125...

Page 7: ...sification without labouring 1 GENERAL DATA 1 1Specifications Gear ratios ahead 2 04 1 2 50 1 3 06 1 Gear ratio astern 2 44 1 common POWER RATING AHEAD RATIO PLEASURE LIGHT COMMERCIAL BHP kW BHP kW 2...

Page 8: ...facilitate servicing 3 2 Gear train The helical Gear train is manufactured from high grade Steel with all Gears being case hardened for long life All Shafts are supported on Taper Roller Bearings whic...

Page 9: ...elp find solutions to potential torsional problems but it is the ultimate responsibility of the person assembling the drive and driven equipment to ensure that they are torsionally compatible 5 2 Chec...

Page 10: ...9 PRM125 BASIC INSTALLATION DETAILS PRM125D Figure 4 Intallation Details...

Page 11: ...Shaft and stern tube to be maintained Whether a solid of flexible coupling is used it is extremely important that the following points are carefully checked i the Coupling should be a tight press fit...

Page 12: ...use in auxiliary sailboats sailing yachts etc Never put the Lever in the position corresponding to the direction of the Vessel 7 ROUTINE MAINTENANCE 7 1 Initial maintenance after 25 hours running Dra...

Page 13: ...tallation Remove examine and replace if necessary Check the alignment of the Propeller Shaft Coupling if necessary rectify by adjusting the Shims under the Engine mounts or the Engine mounts themselve...

Page 14: ...parts in solvent to remove dirt grease and oil Be careful to remove solvent from items before re fitting 9 4 Inspection 9 4 1 Gearcase Inspect for cracks Check sealing surfaces for any scratches damag...

Page 15: ...Gear 24 and remove the Bearing 28 cone Check condition of the O Ring 49 on the Idler Shaft 2 9 6 6 Selector By hand remove Selector Shoe 9 and the Spring 8 Remove the Lever 13 Pass the Selector Contro...

Page 16: ...haft lengths over Bearings to achieve shim requirement Dimension Y A 6 Fit shims as required to within zero to 0 05mm pre load Place the Shims into the appropriate bore of the Front Cover 29 so that t...

Page 17: ...of the Selector Shoe 9 and the Dog Point Grub Screw 17 at max cone eccentricity CAUTION This condition can only be maintained with the clutch at the top dead centre If this is not achieved the gear s...

Page 18: ...SHER 2 23 0563201 NEEDLE BEARING 2 24 MT8406 IDLER GEAR 1 25 001 0270 BEARING 4 26 0672801 THRUST WASHER 2 27 0320470 INTERNAL SPRING RING 1 28 0540252 BEARING 2 29 MT8621 FRONT CASE 1 30 MT8095 BINX...

Page 19: ...18 PRM125 13 Exploded view and Cross section Figure 5 Exploded view and cross section...

Page 20: ...19 PRM125...

Page 21: ...20 PRM125...

Page 22: ...21 PRM125...

Page 23: ...ODUCTS MT8684 KIT 2 1 MT8684 MT8687 MT8688 FORWARD GEAR REVERSE GEAR CONE CLUTCH PRM120 PRM125 MT8685 KIT 2 5 1 MT8685 MT8687 MT8688 FORWARD GEAR REVERSE GEAR CONE CLUTCH PRM120 PRM125 MT8686 KIT 3 1...

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