Commission Regulation (EU) 2017/2400Show full title

2. Definitions U.K.

For the purposes of this Annex the following definitions shall apply:

(1)

‘Transfer case’ means a device that splits the engine power of a vehicle and directs it to the front and rear drive axles. It is mounted behind the transmission and both front and rear drive shafts connect to it. It comprises either a gearwheel set or a chain drive system in which the power is distributed from the transmission to the axles. The transfer case will typically have the ability to shift between standard drive mode (front or rear wheel drive), high range traction mode (front and rear wheel drive), low range traction mode and neutral;

(2)

‘Gear ratio’ means the forward gear ratio of the speed of the input shaft (towards prime mover) to the speed of the output shaft (towards driven wheels) without slip (i = n_in/n_out );

(3)

‘Ratio coverage’ means the ratio of the largest to the smallest forward gear ratios in a transmission: φ_tot = i_max/i_min ;

(4)

‘Compound transmission’ means a transmission, with a large number of forward gears and/or large ratio coverage, composed of sub-transmissions, which are combined to use most power-transferring parts in several forward gears;

(5)

‘Main section’ means the sub-transmission that has the largest number of forward gears in a compound transmission;

(6)

‘Range section’ means a sub-transmission normally in series connection with the main section in a compound transmission. A range section usually has two shiftable forward gears. The lower forward gears of the complete transmission are embodied using the low range gear. The higher gears are embodied using the high range gear;

(7)

‘Splitter’ means a design that splits the main section gears in two (usually) variants, low- and high split gears, whose gear ratios are close compared to the ratio coverage of the transmission. A splitter can be a separate sub-transmission, an add-on device, integrated with the main section or a combination thereof;

(8)

‘Tooth clutch’ means a clutch where torque is transferred mainly by normal forces between mating teeth. A tooth clutch can either be engaged or disengaged. It is operated in load-free conditions, only (e.g., at gear shifts in a manual transmission);

(9)

‘Angle drive’ means a device that transmits rotational power between non-parallel shafts, often used with transversely oriented engine and longitudinal input to driven axle;

(10)

‘Friction clutch’ means clutch for transfer of propulsive torque, where torque is sustainably transferred by friction forces. A friction clutch can transmit torque while slipping, it can thereby (but does not have to) be operated at start-offs and at powershifts (retained power transfer during a gear shift);

(11)

‘Synchroniser’ means a type of tooth clutch where a friction device is used to equalise the speeds of the rotating parts to be engaged;

(12)

‘Gear mesh efficiency’ means the ratio of output power to input power when transmitted in a forward gear mesh with relative motion;

(13)

‘Crawler gear’ means a low forward gear (with speed reduction ratio that is larger than for the non-crawler gears) that is designed to be used infrequently, e.g., at low-speed manoeuvres or occasional up-hill start-offs;

(14)

‘Power take-off (PTO)’ means a device on a transmission or an engine to which an auxiliary driven device, e.g., a hydraulic pump, can be connected;

(15)

‘Power take-off drive mechanism’ means a device in a transmission that allows the installation of a power take-off (PTO);

(16)

‘Lock-up clutch’ means a friction clutch in a hydrodynamic torque converter; it can connect the input and output sides, thereby eliminating the slip;

(17)

‘Start-off clutch’ means a clutch that adapts speed between engine and driven wheels when the vehicle starts off. The start-off clutch is usually located between engine and transmission;

(18)

‘Synchronised Manual Transmission (SMT)’ means a manually operated transmission with two or more selectable speed ratios that are obtained using synchronisers. Ratio changing is normally achieved during a temporary disconnection of the transmission from the engine using a clutch (usually the vehicle start-off clutch);

(19)

‘Automated Manual Transmission or Automatic Mechanically-engaged Transmission (AMT)’ means an automatically shifting transmission with two or more selectable speed ratios that are obtained using tooth clutches (un-/synchronised). Ratio changing is achieved during a temporary disconnection of the transmission from the engine. The ratio shifts are performed by an electronically controlled system managing the timing of the shift, the operation of the clutch between engine and gearbox and the speed and torque of the engine. The system selects and engages the most suitable forward gear automatically, but can be overridden by the driver using a manual mode;

(20)

‘Dual Clutch Transmission (DCT)’ means an automatically shifting transmission with two friction clutches and several selectable speed ratios that are obtained by the use of tooth clutches. The ratio shifts are performed by an electronically controlled system managing the timing of the shift, the operation of the clutches and the speed and torque of the engine. The system selects the most suitable gear automatically, but can be overridden by the driver using a manual mode;

(21)

‘Retarder’ means an auxiliary braking device in a vehicle powertrain; aimed for permanent braking;

(22)

‘Case S’ means the serial arrangement of a torque converter and the connected mechanical parts of the transmission;

(23)

‘Case P’ means the parallel arrangement of a torque converter and the connected mechanical parts of the transmission (e.g. in power split installations);

(24)

‘Automatic Powershifting Transmission (APT)’ means an automatically shifting transmission with more than two friction clutches and several selectable speed ratios that are obtained mainly by the use of those friction clutches. The ratio shifts are performed by an electronically controlled system managing the timing of the shift, the operation of the clutches and the speed and torque of the engine. The system selects the most suitable gear automatically, but can be overridden by the driver using a manual mode. Shifts are normally performed without traction interruption (friction clutch to friction clutch);

(25)

‘Oil conditioning system’ means an external system that conditions the oil of a transmission at testing. The system circulates oil to and from the transmission. The oil is thereby filtered and/or temperature conditioned;

(26)

‘Smart lubrication system’ means a system that will affect the load independent losses (also called spin losses or drag losses) of the transmission depending on the input torque and/or power flow through the transmission. Examples are controlled hydraulic pressure pumps for brakes and clutches in an APT, controlled variable oil level in the transmission, controlled variable oil flow/pressure for lubrication and cooling in the transmission. Smart lubrication can also include control of the oil temperature of the transmission, but smart lubrication systems that are designed only for controlling the temperature are not considered here, since the transmission testing procedure has fixed testing temperatures;

(27)

‘Transmission electric auxiliary’ means an electric auxiliary used for the function of the transmission during running steady state operation. A typical example is an electric cooling/lubrication pump (but not electric gear shift actuators and electronic control systems including electric solenoid valves, since they are low energy consumers, especially at steady state operation);

(28)

‘Oil type viscosity grade’ means a viscosity grade as defined by SAE J306;

(29)

‘Factory fill oil’ means the oil type viscosity grade that is used for the oil fill in the factory and which is intended to stay in the transmission, torque converter, other torque transferring component or in an additional driveline component for the first service interval;

(30)

‘Gearscheme’ means the arrangement of shafts, gearwheels and clutches in a transmission;

(31)

‘Powerflow’ means the transfer path of power from input to output in a transmission via shafts, gearwheels and clutches.