8LT torque motors
8LT direct drive torque motors
Direct drive torque motors from the 8LT series are permanently excited torque motors for applications that require extraordinary dynamic characteristics and positioning precision as well as compact size and reduced weight. These are available in self-cooling or externally-cooled format.
The 8LT series torque motors provide the user with the highest degree of flexibility - the ideal basis for mechatronic and efficient machine design.
All motor components are designed in such a way that saves maintenance.
This motor series features a relatively compact structure with a higher degree of rigidity and more dynamic properties as well as low detent torque. The externally-cooled format additionally ensures intensive surface cooling - the motor does not cause the environment around it to heat up.
The 8LT torque motors are designed as complete motors. Unlike built-in motors, there is no need to install bearings and encoders.
Advantages of B&R direct drives for your application:
- Easy to install
- Small installation dimensions
- Extremely easy to service
- Low costs
- High overload capability/peak torque
- Also available with hollow shaft
- Very good control properties because of low cogging torque
- Available with encoders for functional safety
- When used as a direct drive: No mechanical transfer elements that are subject to wear in the power transmission system, therefore high level of availability and no elasticity in the power transmission system
Embedded parameter chip
All relevant mechanical and electrical information and data is stored in the EnDat encoder used for 8LT three-phase synchronous motors. This means that the user doesn't have to configure settings on the servo drive in the field. As soon as the encoder is connected to the servo drive and power is applied to the electronics, the motor is automatically identified. The motor sends its nominal parameters and limit parameters to the servo drive. The drive then automatically determines the current limits and current control parameters required for optimal control of the motor. The only things that the user has to optimize are the speed and position controllers. The integrated commissioning environment in B&R Automation StudioTM provides all necessary support.
In addition to assistance during commissioning, routine service work is also simplified, and motors can be exchanged without having to take extra time to set parameters.
Cooling / construction type
8LT three-phase synchronous motors with cooling / construction type A are self-cooling and are equipped with a ISO output flange. The motors must be installed on the cooling surface (flange).
8LT three-phase synchronous motors with cooling/construction type B are self-cooling hollow shaft motors.
8LT three-phase synchronous motors with cooling / construction type J are based on motors with cooling type A and are liquid-cooled. The liquid-cooling increases the nominal torque (MN), nominal current (IN), stall torque (M0) and stall current (I0) by 70% as compared to the respective motors with cooling type A.
8LT three-phase synchronous motors with cooling / construction type K are based on motors with cooling type B and are liquid-cooled.
8LT three-phase synchronous motors with cooling / construction type Q are self-cooling and have a shaft with a blind hole. The motors must be installed on the cooling surface (flange).
8LT three-phase synchronous motors with cooling / construction type S are based on motors with cooling type Q and are liquid-cooled. The liquid-cooling increases the nominal torque (MN), nominal current (IN), stall torque (M0) and stall current (I0) by 70% as compared to the respective motors with cooling type Q.
8LT three-phase synchronous motors are available in up to six different lengths. They have different power ratings with identical flange dimensions. The various lengths can be differentiated by a number (d) in the model number (3, 4, 5, 6, 7, 8).
LengthAvailable for size9C1)3Yes1)Yes4YesYes5YesYes6YesYes7YesYes8---Yes
1)Not for 8LTB/8LTK
Feedback systems specified to meet your needs
8LT synchronous motors are equipped with high resolution EnDat encoders. A model is also available with multi-turn encoder. They allow operation without requiring homing procedures or additional measurement systems on the workpiece. The absolute encoder functions without a battery and is therefore absolutely maintenance-free.
With hollow shaft motors, EnDat 2.2 encoders with distance-coded reference marks for absolute position are used.
All 8LT motors rotate clockwise (when looking at the shaft from the front) with th exception of the counterclockwise 8LTB/ 8LTK hollow shaft motors.
Load capacity of the shaft end and bearings
8LT three-phase synchronous motors are equipped with grooved ball bearings which are sealed on both sides and greased. Radial and axial forces (Fr, Fa) applied to the shaft end during operation and installation must be within the specifications listed below. Bearing elements may not be subjected to shocks or impacts! Incorrect handling will reduce the service life and result in damage to the bearings.
The axial forces Fa permitted during the installation of pinion gears, couplings, etc. depend on the motor size and correspond to the values in the "Shaft load" diagram (see "Technical data" section).
The radial force Fr on the shaft end is a function of the loads during installation (e.g. belt tension on pulleys) and operation (e.g. load torque on the pinion). The maximum radial force Fr depends on the shaft end type, bearing type, average speed, the position where the radial force is applied and the desired service life of the bearings.
Axial force, shift in shaft position caused by axial force
The axial force Fa on the shaft end is a function of the loads during installation (e.g. stress caused by mounting) and operation (e.g. thrust caused by slanted tooth pinions). The maximum axial force Fa depends on the bearing type and the desired service life of the bearings. The fixed bearing is secured on the A flange with a retaining ring. The floating bearing is preloaded on the B flange with a spring in the direction of the A flange.
Determining permissible values for Fr and Fa
Information for determining permissible values of Fr and Fa can be found in the motor data for the respective three-phase synchronous motor. Permissible values are based on a bearing service life of 20,000 h (bearing service life calculation based on DIN ISO 281).
8LT three-phase synchronous motors can be delivered with the following options depending on the cooling type and size:
- With various nominal speeds
- With or without an oil seal
- With two different connection directions for the motor connector
The nominal speed is listed as part of the model number in the form of a 3-digit code (nnn). The code corresponds with the nominal speed divided by 100 and preceded by a zero. For example, 1000 rpm would correspond with code 010. If the nominal speed is below 100 rpm, the "nominal speed" part of the order code has an "A" as the first character and then the nominal speed is listed as follows. A speed of 80 rpm corresponds to A08.
The respective combination of other motor options is listed as part of the model number in the form of a 2-digit code (ff).