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12A Beryllium Street, Alrode, Johannesburg

DOT Engineering & Field Services has a long-standing and dedicated team in the engineering field, service specialists in Johannesburg who provide industry-leading solutions, supplying fusible plugs, filler plugs, blanking plugs, and much more. In addition, we provide high-quality industrial fluid drive coupling spares and repairs and industrial safety brake systems. Here we share answers to all your questions about fusible plugscouplings, and encoders.

What is a fusible plug?

Fusible plugs are a safety device that is commonly found in hydraulic systems, closed cell, and fluid couplings. They are considered the last line of defence and are frequently used to prevent a catastrophic failure like an explosion. Safety valves protect machinery from overpressure, while fusible plugs protect machinery from overheating and over pressure and explosion.

What are fusible plugs made of?

Fusible plugs are made of a low melt alloy, housed within a threaded plug body made of brass or steel. The composition if the alloy chosen for the fusible alloy has a predetermined melting point lower than the melting point of the plug body material. For example, tin, bismith and indium with a melting point of 160°C, is a common fusible alloy material.

How does a fusible plug work?

A fusible plug’s fusible alloy is designed to melt at a lower temperature than the plug body. When exposed to temperatures beyond the predetermined plug alloy, the fusible alloy softens and is forced out the plug body by the build-up in internal pressure of the hydraulic system or fluid drive coupling. The plug then has an open port to release pressure and drive fluid which then would halt the drive application and thus stop the drive before further damage is done. This location is usually and open-air space around the plug. Fusible trip plugs do much the same operation as a fusible plug also with a low melt alloy. However, the low melt allot holds down a spring until the predetermined temperature is reached. When the temperature is reached the alloy softens allowing the spring to extend and push out a pin which in turn will strike a proximity switch which would be programmed to shut the drive application down

What is the function of a fusible plug?

Fluid drives as well as other hydraulic application require fusible plugs to reduce significant risk when exposed to excessive pressure and heat build-up, and the system pressure rises until the pressure is too high for the system to withstand. If this happens, the pressure is released. Another risk is that the oil could reach flash point where it may ignite, and this type of failure could be disastrous. Fusible plugs are vital safety system on fluid drive couplings

What is a coupling?

A coupling is a mechanical device used in machines to connect a mechanical power source to a driven machine or dissimilar shafts to transmit power and movement. It is usually a flexible connection that can be removed for service or replacement.

Where are encoders used?

Today’s factories are fully automated, with computers and networks controlling all manufacturing processes, including management, storage, design, transportation, and assembly. These automated machines can perform various tasks like cutting, drilling, welding, and much more.

How does a coupling work?

The coupling maintains a strong but flexible connection between two shafts to transfer motion from one shaft to another. Couplings are designed to specific load application and safety factors to increase the life and maintenance of the driven application.

Why are couplings used?

Bicon coupling Gear coupling Grid coupling Flexible coupling Fluid coupling Spring coupling Jaw coupling Tyre coupling Rigid coupling Curved tooth jaw coupling Nylon Gear coupling Spider coupling HRC coupling Spacer coupling

What are shaft encoders?

Rotary shaft encoders are electromechanical transducers that convert mechanical shaft rotations into a series of electrical output pulses that provide positioning and motion rate data in feedback loops. Standard rotary shaft-angle encoders detect points per revolution, which is the number of discrete positions in a full shaft rotation and corresponds to stepper motor steps per revolution. Rotary encoders are typically packaged in cylindrical cases and are able to detect between a few dozen and several million cycles per shaft revolution. Incremental optical shaft-angle encoders attach to a shaft and rotate between a photodetector unit and an internal light source, usually a light-emitting diode (LED). A series of uniformly spaced transparent or cloudy segments extend from the disk’s centre. An electronics assembly sends signals to a motion controller, which calculates position and velocity data for feedback. Absolute optical shaft-angle encoders rely on multiple light sources, photodetector assemblies, and code discs with annular ring segment patterns. By using a binary output to represent each individual shaft angle as the disc rotates between a radial arrangement of photodetectors and a linear sequence of light sources, providing an absolute measurement.

What is a shaft encoder?

A shaft encoder is a sensor device that is mechanically attached to a rotating shaft and electrically connected to a logic system to provide information about the shaft’s rotation to the logic system.