Commission Delegated Regulation (EU) No 134/2014Show full title

3. Power and torque correction factors

3.1. Definition of factors α₁ and α₂

3.1.1. α₁ and α₂ shall be factors by which the torque and power measured are to be multiplied in order to determine the torque and power of an engine, taking account of the efficiency of the transmission (factor α₂) used during the tests and in order to bring them within the reference atmospheric conditions specified in point 3.2.1 (factor α₁). The power correction formula is as follows:

Equation Ap2.2-1:

where:

P₀

=

the corrected power (i.e. the power under the reference conditions at the end of the crankshaft);

α₁

=

the correction factor for reference atmospheric conditions;

α₂

=

the correction factor for the efficiency of the transmission;

P

=

the power measured (power observed).

3.2. Reference atmospheric conditions

3.2.1. Temperature: 298,2 K (25 °C)

3.2.2. Dry reference pressure (p_so): 99 kPa (990 mbar)

Note: the dry reference pressure is based on a total pressure of 100 kPa and a water vapour pressure of 1 kPa.

3.2.3. Atmospheric test conditions

3.2.3.1. During the test, the atmospheric conditions shall lie within the following range:

283,2 K < T < 318,2 K

where T is test temperature (K).

3.3. Determination of the correction factor α₁ ⁸

Equation Ap2.2-2:

where:

T

=

the absolute temperature of the ingested air

p_s

=

the dry atmospheric pressure in kilopascals (kPa), i.e. the total barometric pressure minus the water vapour pressure.

3.3.1. Equation Ap2.2-2 applies only if:

If the limit values are exceeded, the corrected value obtained shall be stated and the test conditions (temperature and pressure) stated exactly in the test report.

3.4. Determination of the correction factor for mechanical efficiency of the transmission α₂

Where:

• the measuring point is the output side of the crankshaft, this factor is equal to 1;

• the measuring point is not the output side of the crankshaft, this factor is calculated using the formula:

Equation Ap2.2-2:

where n_t is the efficiency of the transmission located between the crankshaft and the measuring point.

This transmission efficiency n_t is determined from the product (multiplication) of efficiency n_j of each of the components of the transmission:

Equation Ap2.2-3:

3.4.1.

Table Ap2.1-3

Efficiency nj of each of the components of the transmission

Type		Efficiency
Gear wheel	Spur gear	0,98
	Helical gear	0,97
	Bevel gear	0,96
Chain	Roller	0,95
	Silent	0,98
Belt	Cogged	0,95
	Vee	0,94
Hydraulic coupling or convertor	Hydraulic coupling9	0,92
	Hydraulic convertor9	0,92