In detail: do-it-yourself repair of the t 25 gearbox from a real master for the site my.housecope.com.
In this article, we will consider the main points that are associated with the action and operation of the gearbox of the T-25 tractor. We will also give a schematic diagram, briefly describe the principle of operation and the most common breakdowns that may occur. And of course, we will give the methods and ways to solve them.
The principle and scheme itself is difficult enough to understand, but we focused on the main working units, so that the study of the principle of operation and possible breakdowns occurs as soon as possible.
All its working mechanisms and assemblies are in a one-piece body. In the frontal part there is a canonical gear, which is made in conjunction with the input shaft and all this rotates on two ball bearings.
The mounting or front bearing is fixed in a special glass with a retaining ring, while the rear one is located between the bulkhead of the gearbox housing itself.
Steel spacers are located under the front bearing flange. They serve to adjust the clearance of side teeth and canon gears. In the middle of the front shaft spline there is a cylindrical main gear of the additional gear (see item 45) and a power take-off shaft.
The ball bearings and gear themselves are fixedly mounted on the shaft with a nut (49) through a bushing (1). Self-tightening gland (2) is located in the bearing cup, which has a longitudinal groove for oil and reduce the pressure load on the gland.
The reverse bevel gear (44) is permanently attached to the input shaft gear, which is fixed in the intermediate portion of the final drive shaft.
Video (click to play).
To the right of the position of the reverse part of the T-25 tractor on the intermediate shaft, a movable gear (5) is fixed - 2nd and 4th gear, to the left is a double movable gear (5) - 1st, 3, 5 and 6th gears.
Also in the movable gears there are annular grooves for the shift fork of the gears themselves.
The intermediate shaft is mounted in the gearbox housing of the T-25 tractor and it is located on two radial bearings (9, 41). It also transmits rotation to the main shaft (24). The built-in movable gear of the doubler is fixed in the middle part.
Below we have given a diagram of the gearbox arrangement of the T-25 tractor, with a detailed description of each item and details.
Let's continue, the gear departs to (32), which is responsible for the rotation of the differential housing.
A device of gears that transmits rotation to the main wheels and allows them to turn at different speeds is called a differential.
At the same time, the speed itself and its speed remains constantly the same.
In the lower area of the T-25 gearbox, there is a unit for additional low gears and the power take-off shaft drive itself. PTO is located along the axis itself, its rotation is carried out using two bearings.
The movement of the moving gears of the gearbox itself is carried out by switching the forks and leashes. They are located on special shift shafts.
These shafts are located above the main shafts of the tractor gearbox and their movement is carried out along the bore, in the side wall of the main gear housing.
The locking mechanism itself performs the function of turning on or off the gears and the reverse clutch with the clutch disc clutch. Also, the locking mechanism prohibits spontaneous disengagement of the reverse gear when the tractor is moving.
At the top of the final drive cover there is a mechanism that is responsible for shifting the reverse and the gear doubler. Below is a diagram of the position of the main gears when others are turned on.
Remember that all mechanisms are inside and are lubricated by the splashing effect of internal oil. Oil level control is carried out by inspecting the plugs, which are located in the lower front and left walls of the block.
Before starting repair work, you need to open the transmission case housing and remove the bearing cover, which is located on the left side of the main shaft. Then remove the PTO cover (fashion selection shaft) on the right.
We unscrew the clamping daw and the spacer sleeve. This will remove the bowl with bearings.
If you need to remove the reverse, then remove the lock washer, it is to the left. It is enough to turn it 30 degrees and remove the stopper from the bearing.
We assemble in the opposite order. During the period of repair or diagnostics, we carefully look at all the details. If we find those close to wear and tear, then we replace them.
The T-25 gearbox is an interesting example of a design solution that made it possible to simplify maintenance of the machine in the field. When developing this unit, special attention was paid to the possibility of replacing individual parts without removing and disassembling the gearbox as a whole.
This is important when breakdowns occur far from service centers or workshops have limited repair equipment.
Various factors influence the fate of a technique. Introduced in 1966, approximately at the same time as the T-28 model, the T-25 tractor turned out to be a more demanded and popular machine. The reason for this popularity lies not only in the general concept of the machine, but in particular in the design of its individual units.
The gearbox of the T-25 tractor is made in a single block with a differential and a main gear. The designers went for some complication of the production technology in order to facilitate further maintenance of the unit and reduce its dimensions.
To do this, a bevel gear made at the same time was placed on the input shaft, transmitting torque at an angle of 90 degrees to shafts and drive mechanisms located in a perpendicular plane. If you look at the assembly drawing of the assembly, you can see that the following are located perpendicular to the input shaft:
Hollow intermediate shaft. Inside this shaft is the power take-off shaft, and outside there are the gears of the second / fourth, first / third and fifth / sixth gears, as well as the reverse mechanism.
The main shaft, on which the gears of the retarder, doubler, first / second and slow gears, driven gears of the third and fifth / sixth gears are mounted.
Differential in the block with gears of the accelerated and decelerated series of transfers, as well as semi-axles.
All shafts are supported by ball bearings pressed into the crankcase housing of the unit, access to which is provided after removing the dowel sleeves or protective sleeves.
A device is installed on the crankcase cover that acts as a gearshift lock when the clutch is not fully depressed. It protects the gear teeth from damage and premature wear.
The design features of the T-25 gearbox allow for partial disassembly of the unit without removing it from the tractor. At the same time, all the characteristics of the node necessary for operation have been preserved:
The number of gears required to ensure the smooth running of the machine under various loads. The early release gearbox has six steps for forward and four reverse, and the later ones, respectively, eight and six.
Optimally matched gear ratios to fully utilize the engine's capabilities.
The reserve of resource and strength required for long-term operation.
The gearbox of the T-25 tractor is equipped with a power take-off shaft, which is necessary for the functioning of various attachments. Due to the change in the number of steps, the gearshift scheme at the checkpoint of later years of production has changed. The algorithm for switching the reverse and doubler remains the same. For this, a separate lever is provided in the tractor control system.
For normal operation in the transmission, it is recommended to use mineral oils with a viscosity of W90 that meet the GL-3 standard. It should be remembered that the T-25 is a tractor developed at a time when the quality of transmission oils was rather low.
Due to the design features of its units, the use of synthetic lubricants of low viscosity can lead to damage to the gearbox. Waste lubricant is removed through an easily identifiable hole in the bottom of the crankcase. There is a hole in the left side of the crankcase for checking the level and filling in new grease.
Thanks to the design features of the transmission, the repair of the gearbox of the T-25 tractor has been simplified, but other problems have appeared that should be paid close attention:
It became necessary to adjust the installation clearances of shafts, gears, bearings and some other parts. This adjustment is carried out using special metal shims of various thicknesses. Painstaking work requires special skills and patience. When done correctly, gears shift accurately and effortlessly, and the gearbox itself works correctly.
Damaged or worn out bushings and bearings lead to the fact that over time, the cast crankcase has to be replaced. To avoid this, the condition of the bearings and other components of the assembly should be monitored.
Despite these shortcomings, the resource of the gearbox of the T-25 tractor is quite high, and the operational characteristics do not cause any particular complaints. The cause of the main malfunctions is the wear of some parts:
Movable gears.
Bearings.
Retainers and rollers.
Gear and reverse forks.
Output shaft stops.
Locking washer lugs and retainer caps.
Input shaft key grooves.
When repairing the transmission, pay special attention to the condition of these parts.
The transmission device of a popular tractor model shown in the diagrams may at first seem overly complicated. But in reality, everything is not so scary, and the maintenance and repair of the unit can be done independently. Of course, if you have the necessary skills and tools.
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The T25 tractor has been a popular agricultural vehicle since the mid-1960s. It was actively used to cultivate land plots and gardens. The drive of this car is rear. The efficiency of the tractor is explained by the fact that it has good technical equipment. The present hydraulic system includes a gear pump through which diesel oil circulates.
A reliable engine and transmission system are installed. They are designed to withstand high loads. The power of this special equipment reached 20 horsepower.
It should be noted that the T-25A model has a 2-cylinder diesel power unit with a dry single-plate clutch. The engine is repairable.
Also, a mechanical speed box is installed here. On the basis of the control scheme attached to the tractor, it is concluded that the speeds are engaged without delay.
The gearbox on the T 25 includes a differential (refers to the transmission housing). The differential consists of gears. Its function is to transfer rotation to the main wheels. The crankcase also has an intermediate, output and input shafts.
It should be noted that there are driven gears on the output shaft.
The tractor can move both forward and backward. Considering this, it should be noted that the number of reverse gears is 6 / forward - 8. Reverse gear is activated by moving the gearshift lever to the rear position, and then to the right side. The speed change occurs when the clutch pedal is fully depressed.The selector lever does not create awkward shifting conditions.
The shift diagram, which is attached to this technique, shows in detail how the gearbox system operates.
The mechanical box has a power take-off shaft. It is a highly durable accessory that powers the attachment's hydraulic system.
A distinctive feature of the checkpoint is that there are no synchronizers. The T 25 gearbox has a doubler and a reverse.
The reverse mechanism is located in the transmission housing, located in the middle of the intermediate shaft. The presence of a drive pulley on the right side of the body facilitates the operation of the tractor.
Thus, the T 25 gearbox is mechanical. The entire automotive system needs to be checked periodically to ensure it is working properly.
Repair of the gearbox of the T 25 tractor is relevant if there are malfunctions in the operation of this system:
