 Pushbelt
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A V-shaped belt between two or more V-belt pulleys has been around for a long time, at least since the advent of a so-called alternator and/or a water pump. The fact that it has regular notches toward the pulleys, thus
making it last longer, only became established later. At that time, it was already being used as a vehicle drive, significantly wider, but still heavily loaded.
This was noticeable, as replacing them was expensive and the transmittable torque was limited. The solution came when they switched from traction to overrun mode. With everything made of metal and running in oil, the
so-called pushbelt was born. Here we're looking at one of the first versions that could still be assembled by hand, so to speak.
These are the hundreds of steel elements that transmit the overrun mode from the drive axle to the output axle. They form a tight sequence, one behind the other, but must be spaced far enough apart to allow the curvature
of two conical discs to be fully extended. The transmittable torques, for example, with Bosch, range from under 150 to over 400 Nm.
This determines the number of high-alloy steel bands between which the elements are suspended. The notches on the left and right, visible above, are precisely matched to this. Multiple bands are used to achieve the
flexibility required with each rotation. Depending on the torque to be transmitted, between 6 and 12 rings are fitted into each other on each side.
kfz-tech.de/PGt57
The width of the pushbelt can also vary between 24 and 30 mm. The belts also have to withstand certain vibrations if torque is no longer transmitted on the return from the output wheel, resulting in a slight reduction in
tension. Perhaps this is one of the reasons why a specific installation direction must be observed for the individual elements and thus for the entire pushbelt.
kfz-tech.de/PGt58
The picture shows that small aids are needed to hold a dismantled pushbelt together. Without even only one of the assembled rings, the whole thing threatens to fall apart. For example, if the belts consist of 12 sub-belts
each, this easily adds up to over 400 individual parts. The belts thus ensure that the elements that transmit the overrun mode stay in place.
kfz-tech.de/PGt59
This would be one of the two wheels, where the torque is transferred either to or from the elements. The angle is relatively steep, which is probably due to the space requirements. This requires even more grip. We're
talking about pressures of up to 700 bar. Of course, the individual steel elements must also have exactly this bevel at the top of their sides.
Each of the 12 rings, for example, is about 2-tenths of a millimeter thick, which adds up to just under 2.3 mm. You can estimate the thickness of the pushing elements yourself if you assume approximately 400 push links
for each of the belts shown here. These must have a defined roughness at the contact surfaces with the conical surfaces, otherwise they will slip on the abundant transmission oil.
kfz-tech.de/PGt60
Here's a completely different design, one that, based on the principle of a bicycle's plate link chain, probably returns from compressive to tensile force. However, the friction principle has been retained, in this case the
crossbars with slightly beveled ends and the cone pulleys. Here, an adjustable pressure is added should the electronics detect slippage.
kfz-tech.de/YGt30
| And just another variation of a pushbelt . . . |
kfz-tech.de/YGt31
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