Yanmar 4LHA-HTP Operation Manual page 546

Chapter 7 Reduction and Reversing Gear
3. Inspection and Servicing
3. Inspection and Servicing
3-1 Clutch case and cover
(1) Check the clutch case and cover for cracking with a
test hammer.
Perform a color check when required.
If the case and cover are cracked, replace those together.
(2) Check for staining on the inside surface of the bearing
section.
Also, measure the inside diameter of the case and cover.
Replace the case and cover if these are worn beyond
the wear limit.
3-2 Bearing
(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 any
abnormal sound is evident, replace the bearing.
3-3 Gear
Check the surface, tooth face conditions and backlash of
each gear. Replace any defective part.
(1 )Tooth surface wear.
Check the tooth surface for pitting, abnormal wear,
dents,-and cracks. iRepair the 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.
Input shaft
Magnetic stand
Maintenance
Input shaft gear
0 . 0 8 - 0 . 1 6
Clutch gear
(0.0031 -0.0063)
Idle gear
0 . 1 2 - 0 . 2 0
Drive gear
(0.0047 - 0.0079)
Output shaft gear
Clutch shaft
Intermediate shaft
Pick-up gauge
mm (in.)
Wear limit
Standard
0.3
(0.0118)
0.3
(0.0118)
3-4 Clutch gear (A) and (B)
(1 (Contact surface with drive cone.
Visually inspect the tapered surface of the clutch gears
(A) and (B) where they make contact with the drive
cone to check if there is any abnormal condition or
sign of overheating.
If any defect is found,
replace the gear.
3-5 Drive cone
(1)Visually inspect that part of 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 overheating are found, replace the cone.
(2)Check the helical involute spline for any abnormal con-
dition on the tooth surface, and repair or replace the
part should any defect be found.
7-1-10
4LHA Seriei
Tapered surface
contact surface
Helical involute spline