5.1 Engine
5.1.2 Engine Starting Preheating System
5.1.2.1 Engine starting preheating system is intended for warming the engine at negative ambient temperatures.
- starting preheater consisting of: heater boiler 11(Fig. 24), pump unit 15 (electric engine, fan, hydraulic and fuel pumps); high-voltage source;
- fuel tank 1 with cock 2;
- preheater control console comprising switches of electric fuel heater, plug, pump unit and solenoid valve. The console is located on the cooling system radiator left side;
- pipelines;
- gas branch pipe 8;
- oil sump casing 6.
The removable burner is bolted to the heat exchanger. Plug 7, solenoid valve 10 in asembly with the injector and electric fuel heater 9 are fitted on the burner.
The solenoid valve cuts in and off the fuel to the burner.
The injector fitted in the solenoid valve body sprays fuel needed for combustion.
The electric heater warms the fuel portion before starting the preheater.
The electric spark firing system ensures inflammation of fuel and air mixture during starting .
The fuel tank contains the fuel stock required for preheater operation. It is connected with engine fuel system via fuel lines, and is always filled with fuel when the engine runs. If need be, it can be filled by means of the engine’s manual fuel feed pump.
The preheater operates as follows: The fuel pump takes fuel from the preheater tank and injects it into the burner under pressure, with solenoid valve opened. In the burner fuel mixes with air, gets ignited and burns, heating the fluid in the heat exchanger. The fluid is forced by the pump through the pipelines, through cylinder block in the direction shown by ar-rows in Fig. 22.
Combustion products are directed via the gas branch pipe under the engine oil sump and warm oil in it. Fuel is cleaned when passing the filters provided in the solenoid valve and injector.
1-fuel tank; 2-straight-way valve; 3,12-drain plugs; 4-feed pipe of the preheater boiler; 5-feed pipe; 6-oil case housing; 7-spark plug; 8-gas driving nozzle; 9-fuel electric heater; 10-electric magnetic valve; 11-heater boiler; 13-air hose; 14-fuel pipe between the pump unit and the boiler; 15-pump unit; 16-outlet pipe;
17-fuel pipe between the heater boiler and the pump unit
Fig. 24 - Engine Starting Preheating System
5.1.2.2 Starting Preheater Service. Remember that violating the operation rules as well as operating a faulty preheater may cause fire. See that there is no coolant and fuel leaks through the joints of pipelines, hoses and cocks; see that the clips on the heat exchanger branch pipes and pipelines are tight.
After truck washing or ford passing remove water which entered the preheater air duct by operating the pump unit during 2-3 min.
Take care that the preheater fuel pump is adjusted correctly.
When preparing the truck for winter operation, proceed as follows:
- screw the transport plug out of the fuel pump drain hole. When returning to summer operation, screw it in;
- open the cock of the preheater fuel tank and leave it opened throughout the winter pe-riod of operation. When returning to summer operation, close the fuel cock;
- check the heat exchanger and pump unit for proper fastening, clean all the instru-ments of dirt; check the wires for good condition and the control console for proper fastening.
Clean the heat exchanger gas duct and combustion chamber. For this purpose disconnect the air supply hose and blow through the heat exchanger, combustion chamber and gas duct. Clean the drain pipe of the heat exchanger burner in order to eliminate fuel accumulation;
- remove carbon deposit from the electrode and insulator of the spark plug. Disassem-ble and wash in kerosene or acetone the injector and its fuel filter as well as the solenoid valve fuel filter;
- check the preheater fuel pump for correct adjustment. The optimum fuel feed to the combustion chamber is determined in service by a steady preheater operation with no flame ejec-tion out of the heat exchanger.
The fuel consumption should be adjusted by the fuel pump reduction valve (Fig. 25). To change the fuel volume supplied through the injector, screw out cap nut 7 on the fuel pump, un-lock adjusting screw 6 and turn the latter to the right for increasing, and to the left for decreasing of the fuel feed.
Preheater operation with naked flame at the outlet is not allowable. On completion of the adjustment lock the adjusting screw with lock nut 5 and screw on cap nut 7.
1- fuel line bolt; 2- swivel elbow; 3,8,9,13-packing rings; 4-union; 5,7-nuts; 6-adjusting screw; 10-spring; 11-ball; 12-fuel pump body; 14-spacer; 15-fuel pump cover
Fig. 25 - Fuel Pump Reduction Valve
5.1.3 Exhaust System
The exhaust system is designed for exhaust gas output and exhaust noise reduction.
There is an auxiliary brake 7 between the exhaust manifold 6 on the engine turbocharger and the inlet pipe 1 (Fig. 26); in order to equalize temperature changes of the parts dimensions and the mutual offset of the engine and the silencer, there is a flexible metal hose 2 behind the front pipe.
The exhaust silencer 4 is fixed by two attachment clips with the supporting brackets on the 2d and the 3d frame cross bars. The exhaust pipe 5 is directed inwards to the vehicle base angularly 40-60°.
1-silencer inlet pipe; 2-metal hose with flanges; 3-silencerintake pipe; 4-exhaust silencer; 5-outlet pipe; 6-exhaust branch; 7-auxiliary brake
Fig. 26 - Gas Exhaust System
5.1.4 Cooling System
The engine cooling system (see Fig. 27) is of liquid, closed type, with a fan viscous clutch built-in; switching on in accordance with the air flow; with forced circulation of the coolant designed for all-season application of the low-freezing coolants.
The coolant analogs and replacements are to be used in accordance with the «YAMZ-6565, YAMZ-65651, YAMZ-65652, YAMZ-65653, YAMZ-65654 Engines and their kitting-up»
Addendum to the Operation Manual «236НЕ2, YAMZ236НЕ, 236Н, YAMZ-236-БЕ2, YAMZ-236БЕ, YAMZ-236Б Power plants».
5.1.4.1 Radiator 14 is of tubular band type, three-line, with a filler. A tight plug provid-ed with the filler. There is a drain plug in the low radiator tank. The radiator is installprovid-ed on the frame 11 which is a bearing element. The radiator has a casing 7.
Before the engine cooling system filling, open the cowling, fill the coolant through the radiator filler 9 till the filler lower edge with the cab heating system valve open. Start the engine for 1 – 2 minutes the air from the system. If necessary, after the engine stop, add the coolant to the filler lower edge and screw the plug in tightly. After that, add more coolant through the expansion tank filler 1 to the «МАХ» on the tank surface; screw the plug 2 in tightly.
5.1.4.2 Expansion tank 1 serves to compensate volume changes of coolant as the latter expands during its heating as well as for air and vapor removal from the coolant. The expansion tank plug 2 is provided with two valves. The gauge pressure in the system being 65 kPa (0.65 kgf/cm2) the outlet valve opens and lets excessive steam pass to the atmosphere, while the inlet valve opens at a pressure of 1-1.2 kPa (0.01-0.012 kgf/cm2).
Truck operation with no expansion tank plug is prohibited!
The material the cooling system expansion tank is made of allows checking coolant level in the tank visually.
1-expansion tank; 2-expansion tank plug; 3-steam hose from the engine; 4- steam hose from the expansion tank; 5-water return hose; 6-fan; 7-casing; 8-radiator; 9-filler with radiator plug; 10- charge air cooler; 11-radiator frame; 12-water supply branch pipe; 13-drain plug; 14- water supply piping from the tank to water pump
Fig. 27 - Cooling System Diagram
5.1.4.3 Monitoring the coolant temperature in the cooling system is carried out using the temperature gauge.
When the temperature increases in the cooling system over a 90 °C, the coolant tempera-ture alarm lights up.
With burning alarm, further travelling is possible with careful observation of the coolant temperature gauge. A short, no more than 10 minutes, temperature rise to 100°C is possible.
5.1.4.4 To drain the coolant from the cooling system place the truck flat, or inclined forward, and unscrew the plug located in the lower radiator tank, the cab heater valve and plug in the heater boiler and pump unit.
In doing so, the plug of the expansion tank filler should be open. The estimated volume of the coolant not drained with the cab heater’s cook being open amounts to 2 l.
Do not run engine upon draining the coolant to remove the remaining water from the sys-tem. That can cause failure of rubber packing rings of cylinder liners, falling out of valve seats, burning-through and distortion of block heads.
5.1.5 Power Unit Suspension
The power unit is mounted on four resilient supports: front, rear and two centre supports
— left and right.
The front and intermediate supports are carrying ones. Rear support is of bearing type, mounted in unloaded condition using adjusting plates 9, according to Fig. 28. The power unit is mounted on beams 3 and 11 with its front and rear supports, with centre — on the brackets which are secured to the truck frame.
Brackets 2, 7, 12 serve as supports for the power unit. Front support bracket 12 is secured to the engine block front cover, while centre support brackets 2 — to the flywheel housing, and rear support bracket 7 to the rear end face of the gearbox.
Cushions 1 of the left-hand and right-hand centre supports are interchangeable.
Also cushions 4 and shock absorbers 5 of the front and rear supports are interchangeable.
0-1 mm clearance between cushion 4 and rear support bracket 7 should be maintained to mount the rear support in unloaded condition.
For this purpose perform adjusting in the following sequence of operations:
1. Unscrew nuts 8 and undo bolts 10.
2. Remove adjusting plates 9.
3. Measure the clearance between bracket 7 and cushion 4. A clearance exceeding 1 mm should be eliminated by using adjusting plates 9.
4. Fit bolts 10 and tighten nuts 8.
1-intermediate support pad; 2-intermediate supports bracket; 3-front support beam; 4-front and rear sup-ports pads; 5-front and rear support shock absorber; 6-front and rear support bracket; 7-rear support brack-et; 8-nut; 9-adjusting plates; 10-bolt; 11-rear support beam; 12-front support brackbrack-et; I- front support; II- intermediate support; III-rear support
Fig. 28 - Power Unit Suspension
5.2 Transmission
The description of clutch and gearbox design as well as instructions for their operation and maintenance are given in the Operation Manual by Yaroslavl Motor Works.
5.2.1 The Hydraulic Clutch Linkage with the Air-over-Hydraulic Booster (AHB)
5.2.1.1 The master cylinder 7, (Fig. 29), is located in the engine compartment and is mounted on the bracket to the cab front panel.
When the clutch pedal is pressed down, the liquid pressure from master cylinder is deliv-ered through piping 16 to the Air-over-Hydraulic Booster (AHB). The liquid in the AHB pushes the rod and opens the pneumatic system valve simultaneously.
The pneumatic part comprises the 10 liter receiver 17, installed inside the left side-member, back-pressure valve 18 and piping. The air from the separate pneumatic part flows into the AHB.
1-reserve tank; 2-tank cap; 3-bolt; 4-nut; 5,14-supporting brackets; 6-cylinder stop; 7-master cylinder; 8-pedal mechanism; 9,26-springs; 10-brake 8-pedal; 11-clutch 8-pedal stop; 12, 15-brake 8-pedal rods; 13-brake valve control lever; 16-hydraulic drive pipeline; 17-nonbrake consumer receiver; 18-back-pressure valve;
19,22-piping; 20-moisture-and-oil separator with four line valve; 21-plug; 23-hydraulic fitting; 24- T-joint;
25-clutch pedal; 27- hose pipe; pedal full travel L=185-190mm; b-clearance Fig. 29 - Clutch Release Control
The back-pressure valve 18 is installed on the receiver and designed for dividing the air-pressure line going from the separate pneumatic system circuit to the receiver for maintaining pressure inside the system irrespective of the pressure drop in the main circuits. The AHB is sup-plied with air through the pipe 19.
5.2.1.2 Clutch master cylinder. During maintenance or assembly install the ring 14 as shown in Fig. 30.
Lubricate the inner surface of the cylinder, as well as the rubber rings and the cup pack-ing with brake fluid when assemblpack-ing.
1-plug; 2,7-rubber rings; 3-pull-back spring; 4-supporting spring cup; 5-supporting spring; 6-inlet connec-tion hose; 8-cylinder barrel; 9-piston; 10-cup packing; 11-locking ring; 12-protecting cover; 13-pushrod;
14-ring; 15-packing ring
Fig. 30 - Master Cylinder
5.2.1.3 The air-hydraulic clutch booster (AHB) has the casing 1 (Fig. 31) which con-tains the piston 5 and the rod 4. The piston and the rod are flexibly packed in the case and can move in axial direction. The piston is packed in the body with the rubber cup packing 9, and the rod is packed with two rubber packing rings 3.
The case is closed with the cap 6 from the piston side, with the rod running through it.
The fork 8 is fixed at the end of the rod, attaching the AHB to the clutch release fork lever. The rubber scraper 7 in the centre of the cap 6 cleans the rod and protects the inside of the casing from dirt.
The exhaust port 10 in the lower part of the casing has a rubber valve. It protects the in-side of the casing from dirt.
The valve 2 in the upper part of the casing removes air from the cavity D. AHB control valve is attached to the casing 1 with two screws; the valve consists of the casing 16, plugged from both sides with the plugs 13 and 19. The slide valve 18 and the air valve 15 are inside the casing 8. The slide valve is flexibly packed in the casing with two rubber rings and sprung to the casing with the cylindrical coil spring 17. The spring 17 pushes the slide valve 18 from the air
1-casing; 2-valve; 3-seal ring; 4-rod; 5-piston; 6-cap;
7-scraper; 8-pusher; 9-collar; 10-outlet port; 11-plug;
12-control valve; 13,19-plug; 14,17-spring; 15-air valve; 16-casing; 18-slide valve; B,C,D,E,F,G,K-cavities; а-compressed air supply; b-working fluid supply
Fig. 31 - Air-hydraulic clutch booster
valve against the stop to the plug 19. The slide valve has an axial bore and a radial bore connect-ing the cavities F and G.
The air valve 15 is pressed to the valve seat inside the casing by the spring 14, discon-necting the cavity E from the cavity F. The unit bore system connects the cavity B with the cavity F and connects the cavities C and G with the exhaust port. The cavities K and D are intercon-nected with the bores. The piping connects the cavity K to the master hydraulic clutch release cyl-inder through tapping in the plug 19. The piping connects the cavity E to the air tank through tap-ping in the plug 13. The cavity E has the exhaust air output for the booster drive control.
5.2.1.4 Clutch pedal adjustment. When the system is fully pumped and there is no compressed air in the pneumatic drive section, adjust in the following way:
- loosen the locknut 11 (Fig. 29) and tighten it against the stop into the pedal;
- move the clutch master cylinder 7 to the upper position in the oblong holes of the sup-porting bracket 5;
- using the support 6 and the screws 3 fix the master cylinder;
- press the clutch pedal up to the stop;
- check when you release the clutch (it should be correct);
- if it is not, release the clutch by moving the master cylinder by 1/2 revolutions of the support 6 and by loosening the screws 3;
- tighten the screws 3 of the master cylinder 7 with the torque 44-56 N.m (4.4-5.6 kgf.m);
- adjust the pedal free travel with the help of the trip 11. The clearance between the push rod 13 (see Fig. 30) and the piston should be b=0.2-0.6 mm which corresponds to the pedal travel of 1-3 mm.
5.2.1.5 Priming. During the brake fluid change or in case of faulty hydraulic part of the drive, prime the system in the following order:
- fill the reverse tank 1 with brake fluid (Fig. 29);
- remove the protective valve cap 2 (Fig.31), put the priming hose on the valve, unscrew the valve by 1/2-3/4 revolutions and dip the hose the hose end into the glassy container with the brake fluid;
- loosen the nut 4 (Fig.29) and tighten it when the first fluid drops appear;
- press the clutch pedal 25 abruptly when the valve is open and depress it smoothly when the valve is closed until the air bubbles from the hose stop. If the air bubbles stopped going out with the fluid, screw in the drain valve.
Check to be sure that the liquid level in the reverse tank is always above the middle and the hose end is always dipped into the liquid. Only in this case the master cylinder does not suck in the air during priming.
The criterion of full priming is a drastic increase of the pedal force when it is pressed by L2=35-40 mm after selecting free travel.
Accelerated priming of the clutch hydraulic drive is also possible with the external source of compressed air. Follow the steps:
- fill the reverse tank with brake fluid;
- remove the protective valve cap 2 (Fig.31), put the priming hose on the valve, unscrew the valve by 1/2-3/4 revolutions and dip the hose end into the glassy container with the brake flu-id;
- put the hose of the external source of compressed air on the cap 2 (Fig.29) of the re-serve 1;
- if the air pressure is not higher than 200-250 kPa (2.0-2.5 kgf/cm2) make sure there are no air bubbles from the piping.
5.2.1.6 The clutch linkage servicing includes regular inspections of the linkage ele-ments, cleaning and the checks of the following:
- hydraulic and air parts leakproofness;
- reserve tank fluid level and threaded joints tightening.
5.2.2 Transfer Gearbox
5.2.2.1 The transfer gearbox (Fig. 32) is mechanic, two-step, with an asymmetrical in-teraxle differential. The transfer gearbox is located on the truck frame fixed by four rubber pads.
The differential is planetary, with four satellite gears, the sun pinion 45 and the crown gear 44. The sun pinion 45 transfers the torque to the shaft 59 of the front axle drive; the crown gear 44 transfers the torque to the rear axle drive shaft 34.
With the operating (unblocked) differential all the axes are steadily driven and additional loads in the transmission are eliminated. Depending on the road conditions the differential can be switched off (blocked), in this case the front and rear axle drive shafts are rotated as a whole.
The front and rear axle drive shafts have the wiper rings 36. The outer surface of the rings has threaded helical grooves which direct the oil when the shafts rotate in the section be-tween the sleeves and the crankcase. The helical groove has different routes: for the front axle drive shaft it is the left route, for the rear axle drive shaft it is the right route. According to the purpose the wiper rings have the stamped letters «П» (front) and «З» (rear). On assembling the transfer gearbox it is necessary to check that wiper rings are correctly installed, otherwise there will be oil leakage through the sleeve.
1-primary shaft; 2,35,60-flanges; 3,27,29,39,61,65-bearing cap; 4,26,31,67-roller bearing; 5,57-bolts; 6,56-pneumatic cylinder cover; 7,55-bushing; 8-shift mechanism housing; 9-neutral piston; 10, 22,54-pistons;
11,49-rod; 12-low gear indicator switch; 13-ball; 14-spring; 15-plug; 16-pin; 17-gear shifting fork; 18-bolt;
19,63-high gear pinions; 20-bushing; 21-gear shift clutch; 23-cylinder; 24,33-low gear pinions; 25-crankcase; 28-breather; 30-lay-shaft; 32-spacer; 34- rear axle drive shaft; 36-wiper rings; 37,40,46,58-ball bearing; 38,66-bearing nuts; 41-differential rear bearing crankcase; 42-differential cage; 43-differential
19,63-high gear pinions; 20-bushing; 21-gear shift clutch; 23-cylinder; 24,33-low gear pinions; 25-crankcase; 28-breather; 30-lay-shaft; 32-spacer; 34- rear axle drive shaft; 36-wiper rings; 37,40,46,58-ball bearing; 38,66-bearing nuts; 41-differential rear bearing crankcase; 42-differential cage; 43-differential