how to choose the right variator belt?
As you know, a fairly large number of Chinese motorcycles, be it a scooter or a snowmobile, are equipped with an automatic transmission with a V-belt variator.
Like any node, it has a weak point. As a rule, this is a variator belt, which sooner or later becomes unusable and must be replaced. It is worth noting that according to the regulations, the belt must be changed every 20,000 km. But don’t think that you shouldn’t look under the variator cover before passing this mark. In addition, if you purchased equipment that is no longer new and how the previous owner treated it, it is difficult to find out at first glance. Therefore, do not be lazy and check the condition of the belt at least before the start of the season, thereby in the future you will save not only wasted time, but also a significant amount of money. So, how can you determine whether it’s time to change the variator belt or whether you can still drive? First, you need to carefully inspect the belt by bending and unbending it. There should be no cracks or tears on it. Secondly, measure the width of the belt
VERY IMPORTANT! The width of the belt must be measured at different points as wear may occur unevenly. Minimum permissible wear 1-1.5 mm depending on the manufacturer
If you still need to replace the belt, be sure to pay attention to its markings (see figure below)
1 – belt length; 2 – belt width; 3 – belt tooth length.
If you cannot read the markings, then take the appropriate measurements and inform the seller so that he can select a similar variator belt.
Belt drives
CVT belts
(GOST 24848.1-81 - GOST 24848.3-81, GOST 26379-84)
A variator is a mechanical transmission capable of smoothly changing the gear ratio within a certain control range.
One type of mechanical variator is a belt variator, where the transmission of torque between the shafts of the mechanism occurs through a variator belt.
Depending on the materials used and the design features of CVT belts, the following designs are distinguished:
— cord fabric variator belt; — corded variator belt in wrapper; — a corded variator belt with open side edges and a molded tooth.
Variable speed belts ensure smooth operation and quiet operation. Depending on the purpose and required power, CVT belts can be smooth or toothed.
The design of the variable speed belt includes several layers:
— a supporting layer based on materials made from chemical fibers (cord cord or cord fabric); - wrapping fabric layer; - one or more layers of rubber (or layers of rubber and fabric) combined into one product.
The load-bearing layer of the CVT belt is located in the longitudinal direction of the belt.
All domestic variator belts, manufactured in accordance with the requirements of GOST 26379-84, are endless with a tightly sealed seam of wrapping fabric.
CVT toothed and smooth belts are used in the following types of mechanical engineering:
— agricultural machinery; — various machines and printing machines; — drives with variable speed; — textile equipment; - in the transmission of many modern cars and scooters.
Variable timing belts are used wherever it is necessary to provide high power and dynamic torque.
Their main purpose is to smoothly, without jerking, change the speed of rotation of the working units. DIMENSIONS OF BELTS SECTIONS in a free state
| Industrial belts | Agricultural machine belts | ||||
| Section designation | Width b0, mm | Height (thickness) h, mm | Section designation | Width b0, mm | Height (thickness) h, mm |
| 1-B16 | 17 | 5 | |||
| 1-B20 | 22 | 6.5 | SV-25 | 25 | 12,5 |
| 1-B25 | 27 | 8 | SV-32 | 32 | 15 |
| 1-B32 | 34 | 10 | SV-38 | 38 | 17 |
| 1-B40 | 43 | 13 | SV-45 | 45 | 20 |
| 1-B50 | 53 | 16 | SV-50 | 50 | 22 |
| 1-B63 | 67 | 20 | (45x22) | 50 | 22 |
| 1-B80 | 85 | 25 | (40x20) | 45 | 20 |
| 2-B25* | 28 | 11 | (28x16) | 32 | 16 |
| 2-B32* | 36 | 14 | |||
Note: 1. Belts marked with * are not allowed to be used when designing new gears.
2. Belts with cross-sectional dimensions in brackets - for agricultural machines in operation and previously designed transmissions for new modifications of combine harvesters. Examples of symbols:
Belt of section 1-B25 with an estimated length of 1000 mm of cord design:
Belt 1-B25-1000 Ш GOST 24848.1-81 - GOST 24848.3-81
Belt of section 1-B25 with an estimated length of 1000 mm of cord design, toothed:
Belt 1-B25-1000 Ш toothed GOST 24848.1-81 - GOST 24848.3-81
Belt of section SV-50 with a design length of 4000 mm of cord fabric construction:
Belt SV-50-4000T GOST 26379-84
Belt of section SV-25 with a design length of 1000 mm with a cord in the load-bearing layer:
Belt SV-25-1000 Ш GOST 26379-84
The same, with cord fabric in the load-bearing layer:
Belt SV-25-1000 T GOST 26379-84
Toothed belt with cross-section SV-25 with a design length of 1000 mm with cord in the load-bearing layer:
Belt toothed SV-25-1000 Ш GOST 26379-84
The same, with cord fabric in the load-bearing layer:
Sponge belt SV-25-1000 T GOST 26379-84
Belt section 45x22 with cord fabric in the load-bearing layer with a design length of 4000 mm:
Belt 45 x 22 - 4000 T GOST 26379-84
The same, with cordsure in the supporting layer:
Belt 45 x 22 - 4000 Ш GOST 26379-84
Toothed belt with a cross-section of 28 x 16 with an estimated length of 1450 mm:
Toothed belt 28 x 16 - 1450 GOST 26379 -84 DESIGN LENGTHS Lp OF BELTS, MEASURED UNDER TENSION
Notes: 1. It is allowed to use belts of intermediate lengths according to the
R40 series of GOST 8032-84
, for example for 1-B25: 710, 730, 750, 825, 850, 875, 900, 925, 1030 , 1060, 1090, 1250, 1280, 1450, 1950... 2. The estimated length is taken to be the length of the belt at the level of the estimated width;
for internal length - the length of the belt along the smaller base. Minimum design diameters of pulleys Upper and lower position of the belt in the pulleys of variator ho and N
Technical requirements.
Pulleys must be made of materials that ensure the required dimensions and operation of the pulleys under operating conditions, i.e. the presence of mechanical forces, heating, abrasion, etc.
Pulleys should not have porosity, bubbles, scratches, or dents on the side surfaces of the grooves.
Defects can only be corrected by gas welding, soldering or a compound based on epoxy resins, ensuring the performance of the grooves is no lower than with soldering.
The roughness of the working surfaces of the pulley grooves Ra should be no more than 2.5 microns according to GOST 2789-73.
The edges of the pulley grooves must be dulled.
The runout of the conical working surface of the pulley for every 100 mm of the pulley diameter, measured perpendicular to the cone generatrix, should not exceed:
— 0.20 mm — at a pulley rotation speed of up to 500 min-1; - 0.15 mm - at a pulley rotation speed of 500-1000 min-1; - 0.10 mm - at a pulley rotation speed of more than 1000 min-1.
Each pulley, when operating at speeds above 5 m/s, must be balanced. Balancing accuracy standards are selected according to GOST 22061-76, but not lower than 5th class of balancing accuracy.
The balancing accuracy is determined depending on the purpose and operating conditions of the machine.
Foreign manufacturers produce the following brands of variator belts:
— ContiTech:
Varispeed® (Varidur, Agridur);
— Optibelt:
Optibelt SuperVX;
- Gates:
Multi-Speed™;
— Goodyear:
Variable Speed;
- Bando:
Power Max®.
When selecting imported belts, do not forget to pay attention to the belt wedge angle - it can be from 26o, and the profile size - from 13x5 mm.
Calculation of gears with variator belts - according to GOST 24848.3-81
Related documents:
— V-belts — Poly-V-belts — GOST 24848.3-81 “Variable V-belts for industrial equipment. Calculation of gears and transmitted powers" - GOST 1284.2-89 "V-belts of normal sections. Technical conditions" - GOST 1284.3-80 "V-belts of normal sections. Transmitted powers" - GOST 1284.3-96 "V-belts with normal sections. Transmitted powers" - GOST 23831-79 "Flat drive rubber-fabric belts. Technical conditions" - GOST 24848.1-81 "Variable V-belts for industrial equipment. Main dimensions and methods of their control"
Scooter variator belt sizes
Using the table provided, you will be able to determine the typical dimensions of the variator belt for your scooter. Select your brand of scooter and see the dimensions (shown in millimeters). The first number is the width of the belt, the 2nd is the length.
Wide V-belts for variators of agricultural machines (combines)
GOST 26379-84
Wide rubber-fabric V-belts GOST 26379-84 are intended for variators of agricultural machines (combines).
- Stretch layer (rubber layer).
- Elastic layer (rubber).
- Supporting layer (cord for belts of cord design).
- Supporting layer (fabric frame for cord fabric belts).
- Compression layer (consists of rubber).
- Wrapper.
Wide variable speed V-belts consist of a load-bearing layer based on chemical fiber materials (cord cord or cord fabric), a wrapping fabric layer and a layer or layers of rubber or layers of rubber and fabric, vulcanized into one product. Belts can be made without wrapping the sides or having a smaller base.
They are used in areas with temperate and tropical climates at ambient temperatures from –30o to +60oC.
Dimensions of belt sections according to GOST 26379-84
| Belt section | SV-25 | SV-32 | SV-38 | SV-45 | SV-50 | 45x22 | 28x16 |
| Large base width | 25 | 32 | 38 | 45 | 50 | 50 | 32 |
| Belt height | 12,5 | 15 | 17,5 | 20 | 22 | 22 | 16 |
| Belt wedge angle (deg.) | 34 | 34 | 34 | 34 | 34 | 40 | 36 |
Wide variable speed V-belts are manufactured with or without molded or cut teeth.
The dimensions of the belt teeth must correspond to those indicated in the table:
| Belt section designation | Belt height between teeth | Groove width | Tooth pitch |
| SV-25 | 8,5-9,5 | 3…5 | 12…16 |
| SV-32 | 9,0-11,0 | 3…5 | 12…16 |
| SV-38 | 9,5-11,5 | 4…6 | 14…18 |
| SV-45 ; 40x20 | 10,0-12,0 | 5…7 | 14…18 |
| SV-50 ; 45x22 | 12,0-14,0 | 5…7 | 14…18 |
| 28x16 | 10,0-12,0 | 3…5 | 12…16 |
Average service life of V-variable belts in operation:
| Purpose of belts | Average belt life, h | ||
| SV-25 , SV-32 , SV-38 , SV-45 , SV-50 | 45x22-3570 , 45x22-3550 , 45x22-2600 , 45x22-2385 , 40x20-2380 , 28x16-1450 | 45x22-4000 | |
| For medium and higher power CVTs designed in accordance with the requirements of this standard | 600 | 600 | — |
| For low-power CVTs with a wide control range, as well as for machines in operation | By agreement between the manufacturer and the consumer | — | |
| For variator drives of the chassis of combine harvesters: with a single-circuit variator and with automatic tension | — | — | 600 |
| With dual-circuit variator, without automatic belt tensioner | — | — | 350 |
The following belts are offered to complete agricultural machinery:
| 28x16-1450 | Belt for mounted header ZHRB-4.2; belt for the Yenisei-1200 combine |
| 38x18-1500 | Belt of the variator of the cleaning fan (thresher), reel, header, variator of the pick-up of the Don combine (TU 38105 1997-91) |
| 40x20-2380 | |
| 45x22-2385 | Belts for combine harvesters "Yenisei", SKD-6 |
| 45x22-2600 | Belt for combines: “Niva”, “Kolos”, “Sibiryak”, SKK-5, SK-SP |
| 45x22-3570 | Drum drive of the Yenisei combine, Potato and beet harvesters, SKPR-6, Kolos, SK-5, Niva |
| 45x22-3750 | Belt for the Yenisei combine harvester |
| 45x22-4000 | Belts for combines "Niva", "Kolos", "Sibiryak", "Yenisei-1200", SKK, KKS, SK-SP |
| 50x33-2660 | Belt for the Yenisei combine harvester (TU 38105 1997-91) |
| 68x24-2600 | Belt for combine harvester “Don”, “Slavutich” (TU 38105 1997-91) |
Belt designation: Belt SV-25-1000 Ш GOST 26379-84 , where:
- SV-25 - belt section;
- 1000 - estimated length in mm;
- Ш - corded load-bearing layer (cord cord).
The same with cord fabric in the supporting layer: Belt SV-25-1000 T GOST 26379-84.
Toothed belt with cross-section SV-25 with an estimated length of 1000 mm. with cord in the supporting layer: Toothed belt SV-25-1000 Ш GOST 26379-84 .
