This clutch is a cone-type, mechanically operating clutch. When the drive cone (which is connected to the output shaft by the lead spline) is moved forward or backward, its taper contacts the large gear and transfers power to the output shaft.

The construction is simple when compared with other types of clutches, and it serves to reduce the number of components, making for a lighter, more compact unit which can be operated smoothly. Although it is small, the power transmission efficiency is high even under a heavy load. Its durability is high and it is reliable as high grade materials are used for the shaft and gear, and a tapered roller bearing is incorporated. Power transmission is smooth as connection with the engine is made through the damper disc.

• The drive cone is made from special aluminum bronze which has both higher wear-resistance and durability. The drive cone is connected with the output shaft through the thread spline. The taper angle, diameter of the drive cone, Twist angle, and diameter of the thread spline, are designed to give the greatest efficiency, thus ensuring that the drive cone can be readily engaged or disengaged.
• Helical gears are used for greater strength. The intermediate shaft is supported at 2 points to reduce deflection and gear noise.
• The clutch case, mounting flange and slide cover are made from an aluminum alloy of special composition to reduce weight. It is also anticorrosive against seawater.
• As the damper disc is fitted to the output shaft, power can be transmitted smoothly. For the damper disc, springs of different strengths are used so that two stages of torque and twist angle are applied. That is, in the first stage, only the weak spring is used, and the strong spring comes into action for a torque higher than a predetermined value. This prevents gear noise due to torsional vibration as well as absorbing shock when engaging.
• The oil level dipstick hole doubles as a breather in addition to being the oil supply port. There is a small clearance between the dipstick and the inside of the dipstick tube which functions as a breather.
• The engagement between the cone and the large gear can be maintained even when the load on the propeller is zero. This is done by the action of the notch and spring joint on the operation lever in the operation device. The operation device can still be used without adjusting the remote operation device when the cone is internally worn, because it is compensated for by the spring joint.
• In order to reduce friction on the operation lever shaft, a needle bearing is used to allow smooth operation.

The shift lever shaft is supported by the side cover in which it rotates. Around the shift lever shaft, there are slots which engage the notch in order to control transmission of rotary power either forward or reverse, or to keep it in neutral. The notch engages each slot by the force of the notch spring.

The shifter is set at the end of the shift lever shaft eccentric to the shaft center line and the angular movement of the shaft (i.e. rotation). The shifter is moved forward or backward along the line of the output shaft and this in turn moves the drive cone forward or backward.

The spring joint contains a spring and 2 spring retainers in the holder, and the remote control joint is connected to the spring retainers so that it can slide a fixed distance. By pushing or pulling the remote control joint with the holder fixed, the remote control joint moves to a position where the two spring retainers touch.

2-2.1 Changing from neutral to forward

The relationship between the spring joint and the notch is as shown in the following figure, and the two spring retainers are the maximum distance apart.

Neutral position

The shift lever is kept securely in the neutral position by notches (A) and (B).

Changing the power transmitting direction to forward is explained below.

The remote control joint forward, when pushed forward moves the spring retainers. The spring is compressed until the two spring retainers touch.

L₁ position of remote operation stroke

The spring in the spring joint is compressed, but the shift lever does not move.

By pushing the remote control joint the holder moves, and the shift lever and the shift lever shaft also move to disengage the notch from the neutral position.

Forced moving position

When the shift lever is forcibly moved through distance L₂ the shifter moves distance t₁. In this position, the drive cone has not yes made contact. However, notches (A) and (B) are disengaged from the neutral notch slot, and notch (A) is positioned on the tapered surface.

The shift lever shaft is turned by the movement of the remote control joint. When the notch touches the tapered part of the forward setting slot, it is pushed by the notch spring force and turns the shift lever forward. At the time time, as the remote control joint is fixed by the two retainers the spring joint being in contact with each other, the holder is moved by the spring reaction so that the shift lever is pushed forward.

By the actions of the notch spring and spring joint, the shifter maintains pressure on the drive cone.

Engaging position for forward

By means of the shift lever shaft tuning force which is caused by the spring in the joint and notch (A), the shifter is moved distance L₃ and engagement is complete. Pressure is maintained on the drive cone after engagement.

2.2.2 Engagement from forward to neutral

Engagement for reverse is the same as for forward, that is, return to the neutral position and move the remote control joint forward.

Engaging position for forward

The drive cone, which is moved by the spring in the joint and notch (A), is kept under force until distance L becomes zero even when the cone is worn.

Position of remote control stroke l₁

The shift lever does not move although the spring in the joint is compressed. The cone is kept in contact due to the transmission of torque when idling.

Forced moving position

The shift lever if forcibly moved though distance l₂, overcoming light friction due to the transmitting torque and the drive cone separates. Notch (A) disengages and notch (B) engages.

Neutral position

The shift lever is returned to neutral by the turning force generated on the shift lever shaft by the spring in the joint and notch (B).

(reference value) [Engine at 1000rpm]

Disengaging stroke:

(1) At the initial stage of usage, the stroke may be heavier than the above value, but the stroke get light when adopted.

(2) Varies according to the idling speed of the engine. The lower the rotation becomes, the lighter the stroke becomes.

(3) The longer the remove control cable gets, the more the cable has the bending positions; the smaller the bending radius becomes, the disengaging stroke gets heavier.[33-C minimum bending radius 203.2mm (8")]

(4) When the spring joint is attached to the shift lever at 52mm distance the center of the lever shaft, the disengaging stroke will get heavier by 15% comparing to the case where the spring joint being attached at 60mm distance.

When the clutch side cover is removed, give the following adjustment at the time of reassembly.

(1) Shift the slot in the drive cone so that it comes to the center of the two large gears.

(2) Set the shift lever at neutral position. (Note that the shift lever can be rotated 360^o when it is removed fro the case.) The neutral position is the position when the shifter comes downwards when the plug is below.

(3) Put the shifter of the side cover at bottom, ant set the shifter to the ditch in the drive cone at the center of the forward and reverse gears. Do not move the drive cone from the center of the two gears at time of the reassembly. (Note that 2mm clearance in diameters are provided in the holes of the side cover, and the gear case. This is for adjusting the difference in the engaging, and disengaging strokes.)

(4) Fit the shift lever locating jig into the holes of the side cover through the 15mm dia. holes as shown.

(5) Put the shift lever in neutral and check the the tip of the lever is aligned the hole A of the jig. If not, loosen the fixing bolt on the shift lever, align it, then tighten the bolt. Take care to leave approximately 0.5mm (0.0197 in.) clearance between the shift lever and the side cover.

(6) Move the shift lever forward or reverse, and check visually the respective distances between the tip of the shift lever and holes B and C, also check the difference between these distances.

(7) When these two distances are not equal, slightly loosen the four setting bolts of the side cover so that it can be moved a little in the shaft direction.

(8) When the distance is larger than normal in the forward setting, move the side cover slightly to the engine side.

(9) When the distance is larger than normal in the reverse setting, move the side cover slightly to the propeller side.

(10) When the distances are equal between neutral and forward and neutral and reverse tighten the setting bolts of the side cover.

(11) Although these distance may be equal both for forward and reverse, there might be some discrepancy between holes B and C due to difference in machining. However, if the discrepancy is the same for forward and reverse there is no problem.

(12) Install the spring joint on the shift lever. (Only when it is dismantled in the boat).

NOTE: When the shift device is removed in the boat, the engine must always be stopped.

(1) Looseness at the connection of the spring joint and the remove control cable.

(2) Looseness of the attaching nut of the spring joint and the shift lever.

(3) To make sure that the value of A, and B is not "Zero" at the engaging position of the remote control lever. If the value is "Zero", un-tighten the bolt of the side cover, and adjust according to the steps described in 2-4.

When the cone for forwards side gets worn, the value of B is decreased, and for the reverse side, the value of A is decreased. When the play in the remote control system is increased, both values of A, and B are decreased.

(1) Always stop the engine when conducting, attaching, adjusting, and inspecting.

(2) When conducting inspection immediately after stopping the engine, do not touch the clutch, The oil temperature is often raised to around 90^oC (194^oF).

(3) Half-clutch operation is not possible with this design and construction. Do not use with the shift lever halfway to the engaged position.

(4) Set the idling speed at between 750 and 800 rpm.

Note: The dual (Two) lever remote control device cannot be used.

(1) Check the clutch case with a test hammer to cracking. Perform a color (dye) check when required. If the case is cracked, replace it.

(2) Check for staining on the inside surface of the bearing section. Also, measure the inside diameter of the case. Replace the case if it is worn beyond the wear limit.

(1) Rusting and damage.

If the bearing is rusted or the taper roller retainer is damaged, replace the bearing.

(2) Make sure that the bearings rotate smoothly.

If rotation is not smooth, if there is any binding, or if an abnormal sound is evident, replace the bearing.

Check the surface and tooth face conditions and back lash of each gear. replace and defective part.

(1) Tooth surface wear.

Check the tooth surface for pitching, abnormal wear, dents, and cracks. Repair lightly damaged gears and replace heavily damaged gears.

(2) Tooth surface contact.

Check the tooth surface contact. The amount of tooth surface contact between the tooth crest and tooth flank must be at least 70% of the tooth width.

(3) Backlash

Measure the backlash of each gear, and replace the gear when it is worn beyond the wear limit.

	Maintenance standard	Wear limit
Input shaft forward gear and output shaft forward gear	0.06 ~ 0.12 (0.0024 ~ 0.0047)	0.2 (0.0079)
Input shaft reverse gear and intermediate shaft	0.06 ~ 0.12 (0.0024 ~ 0.0047)	0.2 (0.0079)
Intermediate gear and output shaft reverse gear	0.06 ~ 0.12 (0.0024 ~ 0.0047)	0.2 (0.0079)
(The same dimensions apply to both KM2-A and KM3-A)
mm (in.)

(1) Contact surface with drive cone.

Visually inspect the tapered surface of the forward and reverse large gears where the make contact with the drive cone to check if any abnormal condition or sign of overheating exists.

If any defect is found, replace the gear.

(2) Forward/reverse gear needle bearing

When an abnormal sound is produced at the needle bearing, visually inspect the rollers; replace the bearing if the rollers are faulty.

(1) Visually inspect the surface that comes into contact with the circumferential triangular slot to check for signs of scoring, overheating or wear. If deep scoring or signs of over heating are found, replace the cone.

(2) Check the helical involute spline for any abnormal condition on the tooth surface, and repair or replace the part should any be found.

(3) Measure the amount of wear on the tapered contact surface of the drive can, and replace the cone when the wear amount exceeds the specified limit.

		Standard dimensions	Limited dimensions
Dimensions l	KM2-A	24.4 ~ 24.7 (0.9606 ~ 0.9724)	24.1 (0.9488)
mm (in.)

NOTE: When dismantled, the forward or reverse direction of the drive cone must be clearly identified.

(4) Measure the dimension of the slot width of the drive cone, and replace the cone when the dimension is over the specified limit.

	Standard dimensions	Standard clearance	Allowable clearance	limited clearance
Slot width of drive cone	8.0 ~ 8.1 (0.3150 ~ 0.3189)	0.15 ~ 0.3 (0.0059 ~ 0.0118)	0.6 (0.0236)	8.3 (0.3268)
Shifter width	7.85 ~ 7.80 (0.3071 ~ 0.3090)			7.7 (0.3031)
mm (in.)

(1) Visually inspect the sliding surface of thrust collar A or B to check for signs of overheating, scoring, or cracks. Replace the collar if any abnormal condition is found.

(2) Measure the thickness of thrust collar A or B, and replace it when the dimension exceeds the specified limit.

Stepped wear	Limit for use
Thrust collar A, t1	0.05 (0.0020)
Thrust collar B, t2	0.20 (0.0079)
mm (in.)

Visually inspect the oil seal of the output shaft to check if there is any damage or oil leakage; replace the seal when any abnormal condition is found.

(1) Spline part

Whenever uneven wear and/or scratches are found, replace with a new part.

(2) Surface of oil seal.

If the sealing surface of the oil seal is worn or scratched, replace.

Visually inspect the spline and the helical involute spline, and repair or replace a part when any abnormal condition is found on its surface.

(1) Needle bearing dimensions, staining

Check the Surface of the roller to see whether the needle bearing stick or is damaged. Replace if necessary.

3-11.1 Shifter

(1) Visually inspect the surface in contact with the drive cone, and replace the shifter when singes or overheating, damage or wear are found.

(2) Measure the width of the shifter, and replace it when the diameter of the shifter shaft, and replace it when the wear exceeds the specified limit.

	Standard dimensions	Clearance	Allowable clearance	Specified limit
Slot width of drive cone	8.0 ~ 8.1 (0.3150 ~ 0.3189)	0.15 ~ 0.3 (0.0059 ~ 0.0118)	0.6 (0.0236)	8.3 (0.3268)
Shifter width	7.8 ~ 7.85 (0.3070 ~ 0.3091)			7.7 (0.3031)
Shifter shaft diameter	9.986 ~ 9.995 (0.3931 ~ 0.3935)	0.005 ~ 0.029 (0.0002 ~ 0.0011)	0.05 (0.0020)	9.95 (0.3917)
Shift lever shaft diameter	10 ~ 10.015 (0.3937 ~ 0.3943)			10.5 (0.3957)
mm (in.)

3-11.2 Notch slot of shift lever shaft

Visually inspect the not slot of the shift lever shaft to check for any abnormal wear or crack; replace any defective part that is found.

3-11.3 Notch

Visually inspect the tip of the notch to check for wear, damage or deformation. Replace the notch if it is found to be defective in any way.

3-11.4 Notch spacing

Visually inspect the notch spring to check for any damage, corrosion or permanent set; replace the spring when it is found to be defective.

Free length	34mm (1.3386 in.)
Spring coefficient	0.459kg (0.992 lb.)
Set length	25.5mm (1.0039 in.)
Set load	3.90kg (8.598 lb)

(1) Check each part for abnormal play, and replace if any play is excessive.

(2) When the movement of each part is not smooth, measure the tension and replace as a complete unit when it exceeds the specified limit.

	Standard Value	Limit value
Tension (st the position of 5mm stroke)	2.8 (6.17)	2.5 (5.51)
kg (lb.)

(1) Spline part.

Whenever uneven wear and/or scratches are found, replace with a new part.

(2) Spring.

Whenever uneven wear and/or scratches are found, replace with a new part.

(3) Pin wear.

Whenever uneven wear and/or scratches are found, replace with a new part.

(4) Whenever a crack or damage to the spring slot is found replace the defective part with a new one.

(1) Remove the remote control cable.

(2) Remove the clutch assembly from the engine mounting flange.

(3) Drain the lubricating oil.

Drain the lubricating oil by loosening the plug at the bottom of the clutch case.

(4) Remove the end nut and output shaft coupling.

NOTE: Take care as it has a left-handed thread.

(5) Remove the oil dipstick and packing.

(6) Remove the fixing bolts on the side cover, and also remove the shift lever shaft, shift lever and shifter.

(7) Remove the bolts which secure the mounting flange to the case body, give light taps to the left and right with a plastic headed hammer while supporting the clutch case with your hand, then remove the mounting flange.

(8) Withdraw the output shaft assembly.

(9) Take out the intermediate shaft and input shaft. When taking out the intermediate shaft, place a bolt or spacer on the shaft hole of the case, and drive the shaft out by tapping it lightly.

(10) Remove the oil sea of the output shaft from the case body.

(11) Remove the outer bearing race from the case body using the special tool.

(12) Remove the oil seal of the input shaft from the mounding flange.

(13) Remove the outer gearing race from the mounting flange in the same way as with the case body.

(14) Remove each adjusting plate from the input or output shaft.

NOTE: The same adjusting plates can be reused when the following parts are not replaced, however, when any part replaced, re-adjustment is necessary.

(1) Take out the reverse large gear, thrust collar A and inner bearing race.

The reverse large gear must be withdrawn using a pulley extractor, by fixing the nut at the forward end in a vice.

(2) Loosen the calking of the forward nut and remove the nut and spacer.

Remove the nut by using a torque wrench after setting the output shaft coupling and fixing the coupling bolt in a vice.

(3) Place the pulley extractor against the surface of he forward large gear, and withdraw the forward large gear, thrust collar A and inner bearing race.

NOTE: Take care as the nut has left-handed threads.

(4) While gripping the drive cone, tip the end of the shaft with a plastic beaded hammer, and withdraw the thrust collar B and inner needle bearing race. A pulley extractor may be used.

(1) Remove the "O" ring.

(2) Remove the thrust washer.

(3) Remove the intermediate gear and needle bearing.

(1) Loosen the bolt of the shift lever, and remove the shift lever from the shaft.

(2) Remove the stop screw for the notch and plug, and take out the notch and spring.

(3) Take out the shifter

(4) Withdraw the shift lever shaft.

(5) Remove the oil seal.

(6) After removing the calking for locking, heat the need bearing potion up to about 100^oC, and extract the needle bearing from the side cover.

(1) Fit the forward side thrust collar B into the shaft.

(2) Drive in the forward end inner needle bearing race using a jig.

(3) Assemble the needle bearing and forward large gear.

NOTE: Check that the forward large gear rotates smoothly.

(4) Fit the thrust collar A and pin, and drive in the inner bearing race using a jig.

NOTES:

1) Drive in with a plastic headed hammer. Do not hit it hard.

2) When fitting the thrust collar A, not the fitting direction. Fit it keeping the stepped surface toward the bearing side.

3) Not that the pin cannot be tightened after the inner bearing race has been driven in.

(5) Assemble the collar and pin so that the pin is in the groove of the collar.

(6) Set and tighten the forward end net. Insert the bolt into the coupling, and fix it in a vice, keeping the spline part upward.

Insert the shaft into the spline of the coupling, fit the spacer, and tighten the nut with a torque wrench.

NOTES:

1) Take care as it is a left-handed thread.

2) Use the reverse side nut used before dismantling as the forward end nut. This is so as not to match the calked portion to the same point.

Tightening torque	10 +/- 1.5 kg-m (61.5 ~ 83.2 ft-lb)
(The same torque applies to both models KM2-A and KM3-A)

(7) Insert the drive cone while keeping the output shaft set for reverse.

(8) Apply procedures 1 through 4 for the forward end.

NOTE: Fit thrust collar A so that the stepped surface faces the bearing side.

(1) Fit the oil seal and bearing outer race in the clutch case.

(2) Insert the input shaft into the clutch case.

(3) Drive the intermediate shaft into the clutch case.

NOTES:

1) If the output shaft is not fitted into the clutch case before driving-in the intermediate shaft, it cannot be assembled.

2) Note the assembly direction of the thrust washer.

(4) Insert the output shaft into the clutch case.

(5) Check the thickness of shims for both input and output shafts. When the component parts are not replaced after dismantling, the same shims can be reused. When the clutch case flange or any one of the following parts is replaced, the thickness of shim must be determined in the following manner.

For input shafts parts: input shaft, bearing.

For output shaft parts: output shaft, thrust collar A, thrust collar B, gear bearing.

1) Measure the distance between the clutch case body and the mounting flange, A or D for each shaft.

2) Fit the outer bearing race to each shaft, and measure the distance (B or C) between bearings.

	A	B	C	D
KM2-A	116.40 ~ 116.75 (4.5827 ~ 4.5964)	115.2 ~ 116.1 (4.5354 ~ 4.5709)	121.48 ~ 122.53 (4.7827 ~ 4.8240)	122.60 ~ 122.95 (4.8268 ~ 4.8406)
mm (in.)

3) Determine the thickness of shim so that the values of clearance and interference after fitting comply with the values in the following table.

Clearance (or interference) for each shaft

Input shaft	+/- 0.05 (+/- 0.0020)
Output Shaft	0 ~ 0.1 (0 ~ 0.0039)
mm (in.)
NOTE: Negative value shows interference.

Adjusting plate

	Part No.	Thickness mm (in.)	No. of shims
Input shaft	177088-02350	0.5 (0.0197)	1
		0.4 (0.0157)	1
		0.3 (0.0118)	2
Output shaft	177090-02250	1.0 (0.0394)	1
		0.5 (0.0197)	1
		0.3 (0.0118)	1
		0.1 (0.0039)	2

 

(6) Fit the adjusting bearing plate to the mounting flange, and drive in the outer bearing race.

NOTE: The outer race can be easily driven in by heating the mounting flange to about 100^oC, or by cooling the outer race with liquid hydrogen [or dry ice].

(7) Apply non-drying liquid packing around the outer surface of the oil seal, and insert the oil sear into the mounting flange while keeping the spring part of the oil facing the inside of the case.

(8) Apply non-drying liquid packing to the matching surfaces of the mounting flange and the case body.

(9) Insert the insert shaft and output shaft into shaft holes of the mounting flange, assemble the mounding flange of the case body, and tighten the bolt.

NOTE: Apply non-drying liquid packing to either the mounting flange or the case body.

(10) Assembly the output shaft coupling of the output shaft, and fit the O-ring.

(11) Tighten the end nut by using a torque wrench, then calk it.

NOTE: Take care as it is a left-handed thread.

Tightening torque	10 +/- 1.5 kg-m (61.5 ~ 83.2 ft-lb)
(The same torque applies to both models KM2-A and KM3-A)

(1) Fit the oil seal and needle bearing to the side cover.

(2) Fit the shift lever.

(3) Fit the notch and spring, and screw in the plug and stop screw.

(4) Fit the shift lever and set the bolt.

NOTE: The clearance between the surface of the side cover and the operation lever is to be 0 ~ 0.5mm (0 ~ 0.0197 in.)

(5) Fit the shifter to the shift lever shaft.

(6) Fit the side cover to the clutch case. Ensure that the shifter engages the grove of the drive cone.

(7) Check that the lever turns smoothly.

NOTE: The lever may not turn smoothly if the hosing is not filled with lubricating oil.

(8) Fit the spring joint, set the remote control cable after adjusting.

For fitting and adjustment refer to the detailed explanation in the appropriate section.