Maz 238 gearbox with range shifter switching diagram

Switching device and circuit

The design and diagram of the MAZ gear shift depends on the gearbox model. There are 5-speed, 8-speed and 9-speed gearboxes.

5 speed

The design of a five-speed gearbox in a MAZ includes such elements as:

• primary, secondary and intermediate shaft;
• rotating bearing;
• gears;
• crankcase, switch and rear cover;
• fasteners;
• container for oil liquid.

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The mechanism that changes gears is located inside the vehicle. When the lever of the switching device changes its position, the articulated joint engages with the recess, which is located on one of the axes. At this moment, the end of the hinge is in rigid engagement with the fork device. The forks fit into the hole on the forward drive gear (gears No. 1, 2, 3, 4) or in the fifth gear position (reverse). A short circuit begins in the torque circuit, causing the secondary axis to begin its movement.

8 speed

The eight-speed gearbox (Gearbox-202) includes:

• crankcase;
• movable gears;
• intermediate shaft;
• constant mesh gears;
• drive shaft;
• splines;
• gear type rim;
• cover;
• driven shaft;
• reverse gear block;
• axial reverse mechanism.

After the vehicle moves and picks up the required speed, you can change gears in the following order: 4H-4B-5H. In order to activate the second speed, you need to wait until the crankshaft speed increases to 2000 rpm. This indicator can be monitored using a tachometer.

It is not recommended to start shifting gears at a lower number of crankshaft revolutions, otherwise the mechanism will fail.

In order to engage reverse, set the switch lever to the down position.

9 speed

The design of the 9-speed gearbox 238 with a range-shifter includes the following parts and mechanisms:

• coupling housing;
• pad;
• gear shift fork;
• right shaft;
• reverse gear washer;
• lazy reverse gear;
• intermediate type roller shaft bearing;
• mounting bolts and nuts;
• spring washer;
• sealing ring;
• retaining ring;
• needle bearing;
• clutch fork bushing.

Before driving, you must disengage the clutch. Before moving off, you need to check the location of the lever; it must be lowered. Switching speed modes is carried out in several stages. At the first stage, it is recommended to use the following switching pattern: 1B-2B-3B. During further movement, you can switch to the pattern: 4H-5B-5H.

Features of the YaMZ gearbox

The YaMZ-2381 (8-speed manual transmission) includes a 4-speed gearbox and a 2-range range multiplier (short divider), which is designed to increase the torque. The YaMZ-238VM model complies with the necessary environmental standards. The presence of an additional box is typical for trucks. The diagram of this box shows the presence of a driveshaft mounting flange here. It should be noted that YaMZ gearboxes can be designed not only for 8 gears, but also for 5, 6, 9, 14.

YaMZ device

YaMZ deviceThe YaMZ-238A version has been discontinued. An excellent alternative to it are models 238ВМ4 (5)(7).

There are synchronizers on all forward gears. Synchronizers ensure not only smooth running, but also silent gear shifting.

An integral part of the YaMZ 238b gearbox is the air distributor. This device provides direct switching of air flows. The mechanism is securely fixed in the upper crankcase cover.

Air distributor YaMZ 238

The article number of the gearbox housing for YaMZ 238 is 1701015. This element has a solid base and is part of the transmission system. Its main function is to protect gearbox parts from dirt, water, and dust. Shafts, bushings, gear blocks, couplings, and nuts are designed for a long working life.

Change of oil

In order to change the oil in a MAZ gearbox, you must:

1. Drive about 5-10 km by vehicle to warm up the old oil in the box. At elevated temperatures it becomes liquid and is easy to drain.
2. 10-15 minutes after stopping the engine, place the vehicle on a lift or inspection pit.
3. Remove the crankcase protective cover.
4. Unscrew the plug and check the volume of oil fluid in the manual transmission.
5. Check the gasket for wear and, if necessary, replace it with a new one.
6. Replace worn filter elements.
7. Open the drain hole and drain the oil into a prepared container.
8. Fill with new oil fluid.
9. Screw on the drain cap.
10. Reinstall the clutch protective cover.
11. Start the engine and check the oil level at various speeds.

An oil change is necessary when maintenance is carried out or gears are difficult to engage.

Divider device for MAZ

1 236-1005055 Ring nut 2 236-1701067-A Thrust ring B-40 3 200-1701192 Lock ring 4 236-1701243 Washer 5 238-1701285 Roller 6 238-1721027 Thrust ring 7 238- 1721033 Thrust washer for intermediate shaft 8 238- 1721048 Intermediate shaft for reduction gear 9 238-1721050 Driven gear of the intermediate shaft 10 238-1721056 Large driving disk 11 238-1721057 Small driving synchronizer disk 12 238-1721061 Thrust ring 13 238N-1721065 Stopper bolt ny 14 238-1721066 Large driven disk 15 238- 1721067 Small driven synchronizer disk 16 238-1721068 Thrust ring 17 238-1721069 Large thrust disk 18 238-1721070 Release spring 18 238-1721070 Release spring 19 238-1721071 Spring retainer 20 238-1721072 Small thrust disc 21 238-1721076 Glass 22 238 -1721078 Damper synchronizer disk 23 238-1721080 Spacer ring 24 238-1721105 Secondary shaft 25 238-1721118-B Gear 26 238-1721125-B Large pressure disk 27 238-1721126-B Press synchronizer disk no small 28 238-1721131 Roller spacer bushing 29 238-1721132 Thrust ring 30 238-1721136-B Small synchronizer disc holder 31 238-1721150 Carriage 32 238-1721240-B Flange 33 238N-1721242-A — 34 3611 Roller bearing 35 503 13 Single row radial ball bearing with locking groove 36 102313 Roller bearing rear 37 102212К1 Front roller bearing 38 70-592708М1 Front secondary shaft roller bearing 39 258072-П29 Cotter pin 40 310067-П2 Bolt 41 311701-П29 Nut 42 312503-П2 Washer Link to this page: https://www.kspecmash .ru/catalog .php?typeauto=6&mark=14&model=84&group=49

How to remove and install the box

Disassembling the MAZ gearbox:

1. Place the truck on a special platform.
2. Remove batteries.
3. Remove air filter elements.
4. Disconnect the mudguards located in the engine compartment.
5. Remove the front suspension cross member.
6. Drain the gearbox oil.
7. Disconnect the speed sensors, reverse switch.
8. Remove the powertrain harness holder.
9. Loosen the mounting bolts.
10. Remove the electric starter from the coupling housing housing without disconnecting it from the wire.
11. Unscrew the front and rear support mechanisms from the gearbox bracket.
12. Disconnect the left support and disengage the input shaft.
13. Remove the gearbox.

In order to put the KAMAZ box in place, you need to repeat all the steps in reverse order.

MAZ divider circuit, description, device

Such devices can easily include a gearbox divider, or, as it is called in technical language, a demultiplier. By the way, you can often hear such names as an additional gearbox or a “transfer case” with a reduction gear.

In fact, this is a device that allows you to obtain a different torque than the MAZ box provides. Range multipliers are used mostly on tractors operating in difficult conditions, where standard gear ratios are simply not enough for the normal functioning of the equipment. It looks something like this:

When driving at a suitable speed on a bad road, the engine in fifth gear works too hard, but if you shift to fourth, you “overclock” the engine, since the speed is too high. But when the multiplier is switched to a lower gear, the gear ratio in the transmission will be averaged between adjacent (in this case 4 and 5) gears. That is, if a MAZ divider is used, the shift pattern for direct gears remains the same, but the number of available gears is doubled.

Such switching is also very useful for those whose cars, although used under normal operating conditions, are subject to frequent load changes. That is, the truck goes empty in one direction, and tows a heavily loaded trailer in the other. In the first case, strictly direct transmissions are used, and when towing, a divider is used.

Consultation on technical issues, purchase of spare parts 8-916-161-01-97 Sergey Nikolaevich

The principle of rapid acceleration of a car with an installed divider on a good road and in difficult conditions is also different. Recommended options are 1B-2B-3B-4N-4B-5N-5B for good coverage and 1H-2H-3N-4N-4B-5N-5B for off-road use.

For all-wheel drive vehicles with a switchable front axle, if they have a MAZ divider, the switching pattern has its own characteristics. If the front axle is disabled, then it will not be possible to engage a lower gear, since this function is simply blocked.

This operation prevents excessive loads on the engine and thereby extends its service life. On our website you can familiarize yourself with the schematic diagram of the YaMZ, MAZ divider installed on Minsk-made vehicles in new modifications. A convenient auto catalog will help you choose the spare parts you need for repairs.

Gearbox 239 YaMZ with a range multiplier (photo, diagram)

Gearbox 239 YaMZ is universal. It is the basis for creating new types of gearboxes for all types of trucks.

General parameters of gearbox 239

The gearbox includes a range (dual-range) with synchronizers (they are only missing in first gear and reverse), a mechanical speedometer drive, and an electromagnetic locking system. It is also possible to equip it with a heat exchange system, which will monitor the temperature of liquids, cooling it in hot weather or heating it in cold weather.

Transmission diagram 239 YaMZ

Upgrading the gearbox 239 with a range-shifter will have two speeds: standard and increased.

The design of the 239 gearbox with range control remains almost unchanged; only more precise speed adjustment is possible.

Gearbox with range multiplier

In general, the operation scheme of the gearbox will depend on the make of the car.

Troubleshooting gearbox 239

The operating time of the checkpoint 239 is determined by how accurately all the conditions of the manual for its use are met. In the event of a breakdown or malfunction, it is important to use the services of a service station or try to fix the problem yourself. Operating and maintenance instructions are available on our website in the appropriate section.

Purpose of checkpoint 239

The YaMZ 239 gearbox is designed for YaMZ-7511 engines of MZKT, KrAZ, MAZ, and Ural vehicles.

MZKT KrAZ MAZ "Ural"

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