Draw wire encoders are devices that measure linear movement of an object by tracking the movement via reel mechanism and rotary encoder.
Eltra wire encoders
Company Eltra s.p.a. manufactures two series of wire encoders. These devices have already proven themselves in storage systems, extruders, elevators, presses, etc. Due to simplicity and compactness, they can be used in almost all industrial applications where linear measurement is present.
The Italian company produces two series of devices with such operating principle:
One of the main differences between the models is the rope material. The FE series uses a Dyneema rope, while the FES series uses a steel one. Both models consist of a rotary encoder and a wire draw mechanism.
Principle of operation
The working principle of wire encoders consists in the interaction between drum with a wire and a rotary sensor. Such system works like a tape measure or a fishing reel.
The rope’s eyelet is mechanically attached to the measured object and the string is unwound during its movement. Built-in sensor detects and tracks the length of the pulled rope. Such measurement system may help to avoid the use of standard linear devices. It is very popular in a wide range of different applications, for example, shop floors, manufacturing lines, and off-road vehicles.
Eltra FE encoder with Dyneema rope
The devices in this series use a special string made of Dyneema material (HPPE - High Performance Poly Ethylene).
The main advantages of such material are its small weight and very high resistance against mechanical damage. Due to its robustness, it is used in many industrial areas even in the military industry (for manufacture of equipment and body armor).
Presented string also has good protection against influence of chemicals and ultraviolet radiation. Dyneema has a very low elongation (less than 1.5 %).
FE Series may be produced as incremental or absolute rope encoder. It depends on the type of sensor that connected to the drum.
The following Eltra encoder models are available for rope installation:
- EH 30M (incremental kit)
- EL 53B (incremental)
- EAM 53B (absolute)
All devices have an optical principle of operation. To determine general measurement specifications of the whole system, it is need to refer to the relevant characteristics of connected sensor.
After mounting the encoder to the reel letter "F" is added to its ordering code. For example, the encoder of the EL 53B series will become FEL 53B, and the EH 30 M will become FEH 30 M.
Eltra FE reel features
The company manufactures two types of drum options that belongs to the FE series:
The number indicates the stroke length of each model in millimeters (FE 1500 = 1500 mm).
FE 1500 has a wire length of 1500 mm and a linear error of ± 0.75 mm. Drum circumference of the model is equal to 120 mm. The housing is made of painted aluminum and can work optimally at temperatures up to 70 °C (158 °F). The weight of the entire structure (without encoder) is only 500 g.
FE 4000 has a wire length of 4000 mm and a linear error of up to 2 mm. The housing mechanical characteristics is similar to the previous model. The IP protection level for both series is depend on encoder type. The final weight of the assembly with the case is 1100 g.
For mechanical coupling to the measured object, the eyelet is used. The string is capable to moving with speed up to 85 m / s.
FES Eltra encoders
The devices of the FES series are available with a steel rope with length of up to 15 m and can be paired with an incremental or absolute encoder. This type is perfect solution for harsh environment as it has high resistance against mechanical damage.
The following Eltra encoders are available for mounting in assembly:
- ER 58 B (incremental)
- EAM 58 B (multiturn absolute)
- AAM 58 B (multiturn absolute)
The serial number is generated using the same principle as the previous category, that is, the letter "F" is added to the sensor order code.
Eltra FES reel characteristics
Eltra produces three models with different rope length:
- FES 3000
- FES 6000
- FES 15000
FES 3000 has a wire with length of 3 m and diameter of 0.87 mm. Drum circumference is 200 mm. The maximum travel speed can reach up to 0.8 m / s. The main body may be made of aluminum or plastic. Its total weight is 350g (without sensor).
FES 6000 uses a rope with length of 6 m and diameter of 0.54 mm. The repeatability of the results here is identical to the previous series and equal to + -0.15 mm. However, it has faster traveled speed, which can reach up to 3 m/s. The housing is made of aluminum or plastic and has a weight up to 700g.
FES15000 has a 15 m wire with a diameter of 0.87 mm in its design. That feature makes series the owner of the biggest stroke length in entire manufactured products. This is the maximum distance that standard models can work with. The speed of movement can reach up to 2.4 m / s. The housing is made of aluminum die-casting. Available two models: with standard steel or synthetically coated rope. The total weight of the structure is 2500 g (without sensor).
All three series may work with temperatures up to +80C (176F). Before starting, it is recommended to make a 5 mm wire extension before starting point. This will help to prevent wire from snapping. Work should be carried out only along one axis, that is, along single line.
On the website of our company eltra-encoder.eu you can find all the presented models. If you want to get more information about availability in stock and terms of delivery, please contact our managers.