Tap-15 or Tad-17. What's thicker? Differences
Tap-15 or Tad-17: differences
Tap-15 or Tad-17? If we consider the chemical composition of these lubricants, then there are few differences. Both belong to the mineral, as they are made in the process of distillation and distillation of certain grades of oil. Tep-15 is cheaper, and therefore the concentration of extreme pressure and antiwear additives is reduced there. In addition, the viscosity of Tep-15 is somewhat lower, although for many moving parts of cars (especially domestic production), this indicator is not critical.
The safety of using the gear lubricants under consideration is determined not only by the intensity of their thickening at low temperatures (for Tad-17, the operating temperature range is -20 to +135ºC, and for Tep-15 from -23 to +130ºC), but also the degree of chemical aggressiveness in relation to stuffing box seals. In this sense, Tad-17 is more active. It contains sulfur and phosphorus in greater amounts, which contributes to mechanochemical reactions on the surface of hypoid gear parts. As a result of such reactions, films are formed there that increase the anti-seize ability of the material under conditions of high sliding speeds of one transmission element over an adjacent one. In such conditions, not all brands of rubber seals may have sufficient wear resistance. Moreover, if the synchronizer is made of copper or a copper alloy, then its resistance will also be reduced.
On the contrary, Tep-15, which does not contain such a quantity of chemically active reagents, is less sensitive to the degree of oil resistance of rubber and the grade of copper alloys.
What is thicker - Tap-15 or Tad-17?
When comparing, it is important to evaluate not only the absolute value of viscosity, but also its change in the process of increasing temperature.
Tep-15 brand oil according to GOST 17479.2-85 belongs to gear oils of the 2nd group, it contains only antiwear additives, and therefore is designed for effective use under external loads up to 2 GPa and bulk temperatures up to 130ºC. At the same time, Tad-17 also includes extreme pressure additives, and belongs to group 5, for which external loads on shafts and gears can reach 3 GPa or more, at bulk temperatures up to 150ºC.
Thus, the optimal units for the use of Tep-15 are cylindrical, bevel and - partially - worm gears, which operate at relatively low sliding speeds, and for Tad-17 - predominantly hypoid gears, where such speeds reach 5 ... 7% of the rotation speed gear pair. Accordingly, the wear indicator in such conditions increases from 0,4 to 0,5.
Evaluation of the stability of viscosity indicators depending on the temperature in the volume of the node gives the following values. For Tep-15, the viscosity changes as follows:
- At 100ºC - 15… 16 mm2/from.
- At 50ºC - 100… 120 mm2/from.
- At 20ºC - 870… 1150 mm2/from.
Accordingly, similar indicators for Tad-17 are:
- At 100ºC - 18… 20 mm2/from.
- At 50ºC - 180… 220 mm2/from.
- At 20ºC - 1500… 1600 mm2/from.
All the same, Tap-15 or Tad-17? Comparing the performance of lubricants, we conclude that the load capacity of Tad-17 gear oil is higher, therefore, it can be used at increased loads on the mechanism, where the long-term existence of a surface oil film separating the rubbing parts is mandatory. At the same time, Tep-15 is more effective for use in tractor gearboxes, as well as medium-duty trucks.
