Gearbox
Gearbox manufactured by JSC "SAAZ AMO ZIL" - mechanical, five-speed, synchronized, with a central control lever, with direct or overdrive fifth gear. The gearbox lever is connected by a rod to the gear shift lever at the driver's workplace. The design of the gearbox and its drive is shown in Fig. 1 and Fig. 2.
1 — primary shaft; 2 — secondary shaft; 3, 6 — synchronizers; 4 — cover; 5 — control mechanism; 7 — cover of the rear bearing of the secondary shaft;
8 — speedometer drive worm; 9 — secondary shaft flange; 10 — secondary shaft flange nut; 11 — speedometer drive; 12 — first gear and reverse gear;
13 — intermediate shaft; 14 — second gear gears; 15 — reverse drive gear and power take-off; 16 — third gear gears; 17 — gears of the fourth (fifth) gear;
18 — intermediate shaft drive pair; 19 — crankcase; 20 — input shaft cover; 21 — intermediate reverse gear and power take-off
Gearboxes of the following models can be installed on the bus: SAAZ-3206, SAAZ-320670, SAAZ-132A2, SAAZ-132M3.
The new family of SAAZ-136 gearboxes has an increased service life and the following differences from the SAAZ-3206:
- all gears on the secondary shaft are mounted on needle bearings;
- the intermediate shaft gears have a keyless fit on the shaft due to interference;
- the intermediate shaft is mounted on tapered bearings, the tightening of which is regulated by a special nut;
- the SAAZ-136M has clutch synchronizers installed in all gears, the SAAZ-136A has finger synchronizers with steel cone rings coated with molybdenum;
- a contactless speedometer sensor is installed.
For better use of performance properties, it is recommended to use buses with gearboxes with an overdrive 5th gear on suburban routes, and buses with gearboxes with a direct 5th gear on city routes.
For oil filling there is a filler screw plug in the right wall of the crankcase 19. To drain the oil, there is a drain hole in the left wall of the crankcase, at the bottom, closed with a magnetic screw plug. The box is centered along the flange of the input shaft cover 20.
1 — lever handle; 2 — gear shift lever; 3 — hinge; 4 — lever bracket; 5 — rod; 6 — bolts; 7 — pin; 8 — coupling; 9 — fork; 10 — gearbox; 11 — shift lever
Gear changes are made by the control mechanism lever in the cover 4 (Fig. 1) of the gearbox through rod 5 (Fig. 2) and gear shift lever 2 at the driver's workplace. If it is difficult to shift gears, it is recommended to adjust the drive by changing the length of the rod 5 by turning the fork 9 of the gear shift rod.
When servicing the gearbox, its fastening to the clutch housing and the fastening of the parts of the gearbox itself to the crankcase are checked; the oil level is replaced and maintained according to the lubrication chart. When changing the oil, you need to clean the drain plug magnet and the breather. A clogged breather can cause an oil leak due to increased pressure in the crankcase. When changing the oil, as well as when repairing the gearbox, do not allow contaminants to get into it, which can cause the gears to jam.
Possible Gearbox Malfunctions and Methods of Elimination
Difficulty engaging all gears
- Incomplete disengagement of the clutch (clutch "drives") — Adjust clutch pedal free play.
Shifting gears with a bang and a grinding noise
- Wear of synchronizer cone rings — Replace synchronizers.
- Wear of the locking chamfers of the pins and carriage — Replace synchronizers.
Self-disengagement of gears while driving
- Incomplete gear engagement due to a faulty switching mechanism — Troubleshoot.
- Wear of forks — Replace worn parts.
- Loosening of forks and heads — Tighten the fastening.
Gears do not engage
- Breakage of pins and synchronizer clamps — Replace synchronizers.
Increased noise during gearbox operation
- Loosening of fasteners — Tighten fasteners.
- Wear and breakage of gear teeth — Replace worn parts.
Oil leak from gearbox
- Wear or loss of elasticity of oil seals — Replace oil seals.
- Increased pressure in the crankcase — Clean the breather.
- Violation of tightness along sealing surfaces — Tighten fasteners, replace gaskets.
