Monthly Archives: April 2018

Beemo Works With Raspberry Pi

Even adults watching Adventure Time wish to own a personal BMO, the quirky living game system from the Be More episode of the show. Although based on the GameBoy, BMO is a digital friend calling out through the nostalgia lens of our childhood times. Now Bob Herzberg has created Beemo, a BMO for his daughter and her friends.

In building the living little boy, Beemo, Herzberg used the popular single board computer Raspberry Pi (RBPi), which be runs on battery power, a USB battery pack. Although his body is made from laser-cut MDF wood, Beemo uses am 8-inch HDMI monitor. Herzberg had to 3-D print the arms and legs, attached them to the body, which he sanded, sealed, and painted. Adding some vinyl lettering completed the look. Adding a small wireless keyboard meant Beemo could be remotely controlled.

To interface the gaming button on the panel, Herzberg had to create a custom PCB, and he laser-cut the special acrylic buttons to mount them. These he connected to the IO header on the RBPi to make them work. Another PCB functions as a holder for the USB sockets. This allows Beemo to have USB ports on the front panel. Beemo works comfortably for a continuous 8-hour period on his battery.

Herzberg’s daughter created the custom animations that he then transformed into MP4 video files—giving Beemo most of his personality. The remote keyboard operations turn the animations on. Some BMOs are given an internal microphone and a speaker. The BMO translates the user’s voice using Google Voice API, and maps it to an appropriate response, allowing the user to have a conversion with BMO.

Herzberg also used the RBPi camera module. Some BMO makers use servos to make the camera pop out for taking a snap. This type is called the GoMO and it can take pictures. Actually, there is a whole family of MOs—GoMO, CMO, XMO, UMO, and a few others. Although people like to think of the retractable camera as a ghost detecting equipment, Beemo simply likes to take nice photos.

Playing games with Beemo is very simple. You only have to load one of the emulators Raspbian supports. Raspbian is the operating system that makes RBPi run. Herzberg faced some real challenges when creating Beemo. He had to use different materials and techniques to fabricate the enclosure. However, the presence of the RBPi inside meant bringing Beemo to life was much simpler.

While Beemo may not be able to hop around and sing as the BMO in Adventure Time did, he can certainly play a huge number of retro games, because of the RBPi within him. As Herzberg was familiar with the Atari 800 emulator, having written games for that platform earlier, he used the front panel USB ports for connecting gamepads. Of course, the D-pad and front panel buttons are also equally useable.

Herzberg uses the RBPi A+ as the heart of his project. He has split 256 MB of the RAM between the CPU and the GPU. He also uses the composite video and stereo outputs on the 4-pole jack internally. By modifying the config.txt file, he was able to shut off HDMI output completely.

Control the OpenGarage from Anywhere

All of us have our forgetful moments such as not having closed the garage door after leaving home, and that has us worried and stressed until we can get back. At times like this, we miss the advantage a remote garage door would have given us. Although automated garage door openers are readily available, they use proprietary software, which we may not be able to tailor to our requirements.

OpenThings now offer OpenGarage, an intuitive and easy-to-use garage door monitoring and controlling device. Apart from monitoring the door status remotely, the user can also close or open it from anywhere. Apart from this, you can also check the history, receive notifications, and even use the automation feature to auto-close the door. Now, even if you have forgotten to close your garage door, with OpenGarage, you can access, monitor, and control it from your office, home, or while traveling on the road. OpenThings offers a free app for use on your mobile, and it allows you to remain in contact with OpenGarage always and from anywhere.

However, the greatest advantage of OpenGarage is it is an open-source product. That means you can easily access the complete software code, and customize it to fit your own specific need. As it is a Wi-Fi enabled gadget, OpenGarage has a built-in ultrasonic distance sensor and a relay. You can modify it to use it as a sump pump controller by monitoring the water level in the sump, or use it as a parking sensor for making sure the car is parked at the required safe distance.

If you do not want to use OpenGarage to control a garage door, you can connect more sensors to it, such as humidity and temperature sensors, and use it as a Wi-Fi enabled weather data logger. The instruction video OpenThings provides makes it very quick and easy to install OpenGarage.

There are several advantages of using OpenGarage and its accompanying app. Apart from the ease of accessing, monitoring, and controlling your garage door remotely, using the intuitive OpenGarage UI on your mobile means you do not need to carry an extra remote control unit. The app shows the present status of the door on your screen, and you can always toggle it open or close.

OpenThings places updates for their device and app on the OpenGarage Github repository. That makes it easy to use the web interface for updating the firmware in the device—simply click on the update button at the bottom of the page.

Sometimes the update may fail due to various reasons. You can then do a factory reset by holding the button on the device—keeping it pressed for about 5 seconds—then follow the steps for setup. If this step also does not work, simply use a USB cable to flash the new software, following the instructions.

OpenThings has designed the OpenGarage app to enable control over several units that may be required in a multi-garage setup. Therefore, not only is this web-connected door opener useful for individuals alone, it is useful for commercial garages as well.

Do Air Conditioners Need Inverters?

With the economy jumping around and the cost of electricity traveling north, consumers now prefer to buy appliances that guarantee payback through long-term savings. As old gadgets, especially air-conditioners become non-functional, more and more users are replacing them with appliances using inverter compressor technology. This not only uses energy more effectively, it saves the user from paying large electricity bills.

While regular air-conditioners consume a fixed amount of energy depending on the temperature setting, those using the inverter compressor technology consume only the power necessary for the cooling—ensuring maximum savings of electricity, while offering maximum comforts to the consumers.

With rivers running dry in most parts of the world, dams are no longer producing enough electricity to sustain entire cities. That is forcing people to purchase environmentally friendly products that utilize electricity effectively. When the temperature difference is low, such as during the night, a regular air-conditioner does not reduce its power intake, but those using the inverter technology automatically slow down the compressor so that it consumes less power. When the compressor speed varies with temperature difference, and it consumes electricity only as needed, energy requirement reduces by as much as 30-50%.

While the inverter technology is more expensive, equipment using the technology pay back over time with savings through lower power consumption. Acting as heat pumps, air-conditioners with inverter technology are highly efficient at utilizing lower energy compared to their regular counterparts.

Another advantage in using the inverter technology is the relatively quiet nature of its operation. Regular home appliances such as air-conditioners and refrigerators are notorious for their noisy operation, especially noticeable at night, when the ambient noise levels are lower. As the inverter technology is quieter, users can enjoy better sleeping times.

As the compressor speed adjusts itself with temperature fluctuations, the device using the inverter technology runs with greater stability, ensuring the durability and a longer life span for the device.

For the more technically oriented, inverter technology works with DC motors of the compressor in a refrigerator or air-conditioner, controlling the speed of the motor, thereby continuously regulating the temperature. The inverter units usually have a variable-frequency drive for controlling the speed of the compressor motor, resulting in better control of the cooling or heating output.

In practice, the drive converts the incoming AC into Direct Current and using pulse width modulation creates the desired frequency for operating the motors. A micro-controller does all this including sampling the ambient temperature to control the speed of the compressor.

Compared to the regular air-conditioners and refrigerators, the inverter units have increased the efficiency of operation, extended the life of various parts, and have avoided the sharp fluctuations in temperature.

With a quieter operation, lower operating costs, and requiring lower maintenance, inverter air-conditioners units are better than regular constant speed air-conditioners are. Although these new type of air-conditioners are more expensive, they balance this with their lower energy bills. Although it depends on the actual usage, the payback time is usually two years on average. Modern air-conditioners are typically split units, with the heat exchanger placed outside for higher efficiency.

What is a Hygrobot?

In the future, tiny robots such as the hygrobot will be able to avoid the need for batteries and electricity to power them. Like a worm or a snake, moisture will power these tiny wriggly robots.

Hygrobots actually inch forward by absorbing humidity from their surrounding environment. Created by researchers at the Seoul National University, South Korea, these tiny robots can twist, wriggle forwards and back, and crawl just as snakes or worms do. The researchers envisage these hygrobots being useful for a variety of applications in the future, which could include delivering drugs within the human body.

According to the researchers, they received the inspiration for hygrobots from observing plants, and they have described their findings in the journal Science Robotics. Using hydroexpansion, plants change their shape and size when they absorb water from the air or ground. For instance, pinecones know when to close and when to open, depending on whether the air is wet or dry, and this helps them to disperse seeds more effectively. Even earlier, plants have provided inspiration for robots—researchers created robots in imitation of algae.

Although hygrobots are not made of plant cellulose, they mimic the mechanism the plants use. As moisture is available almost everywhere, using it as a source of power for operating robots makes sense. Unlike batteries, moisture is non-toxic, and does not have the tendency to explode. This is an important consideration, as microbots, for instance the spermbot, are usually required to operate within the human body.

One can visualize the motion of hygrobots by observing the Pelargonium carnosum seed bristle—a shrub-like plant found in Africa. The hygrobot mimics the motion of the bristles, as it has two layers made of nanofibers. While one layer absorbs moisture, the other does not.

Placing the bot on a wet surface causes the humidity-absorbing layer to swell up, making the bot move up and away from the wet surface. This allows the layer to lose moisture and dry up, and the bot comes back down—the cycle repeating itself—allowing the bot to move. The researchers demonstrated a hygrobot coated with antibodies crawling across a bacteria-filled culture plate. It could sterilize the entire plate without requiring any artificial power source.

This is how the researchers imagine the bots of the future will deliver drugs within the human body, propelling themselves using only the moisture of the skin. Other than responding only to water vapor, researchers say they could equip them with sensors that respond to other gases as well.

However, this is not the first instance of scientists working with tiny robots. Last year, researchers had created a hydrogel bot for biomedical applications that a magnet could activate. It was able to release localized chemo doses for treatment of tumors.

Not only medical, military, and industrial applications will also benefit from light and agile microbots that do not require additional power inputs to operate. Hygrobot, the biologically inspired bilayer structure harnessing energy from the environmental humidity uses ratchets to move forward. The hygroscopically responsive film quickly swells and shrinks lengthwise in response to a change in humidity.

GrovePi Kits for the Raspberry Pi

If you are looking to interface sensors to the Raspberry Pi (RBPi), the popular single board computer, GrovePi+ from Dexter Industries (SEED Studios) makes it very easy with their starter kit. The kit carries a GrovePi+ board, including more than 10 carefully selected sensors along with the necessary interfacing cables. The kit is very easy to use, as the user only has to plug the GrovePi+ board over your RBPi, and connect the necessary sensor to the board. GrovePi provides a powerful platform for any user to start playing with sensors and hardware.

The simplicity of the GrovePi+ board is evident, as you do not need any other hardware connection—only plug in the board atop the RBPi and initiate communications between the two boards over an I2C interface. The GrovePi+ board acts like a shield and the user can connect any of the Grove sensors from the kit to the universal Grove connector on the board, using the universal 4-pin connector cable available with the kit.

The GrovePi+ board has an ATMEGA328 micro-controller on it, and the Grove sensors, both analog and digital, connect to it directly. The RBPi also communicates with this micro-controller, which performs as an interpreter for the Grove sensors, sending, receiving, and executing commands the RBPi sends it. You can use any RBPi model with the GrovePi+, selecting from among RBPi A+, B, B+2, or B+3

GrovePi+ forms the hardware system for connecting, programming, and controlling sensors that help build your own smart devices. GrovePi+ is small—the size of a credit card—however, it is very powerful. You can think of the GrovePi+ kit as an Internet of Things kit for the RBPi—allowing you to connect numerous sensors to the RBPi—simply by connecting a cable from the GrovePi+ board to the sensor. The manufacturer’s website offers several software examples you can download and try. Alternately, you can write your own programs for the RBPi to control and automate any device.

GrovePi+ does away with the need for connecting sensors to the IoT using breadboards and soldering the sensors. Now it is only necessary to plug in the sensors and start programming directly. Therefore, GrovePi+ is and easy-to-use modular arrangement for hacking your hardware with the help of the RBPi and the Internet of Things.

Using the GrovePi+ system, one can connect over 100 types of sensors to the RBPi. The collection of sensors offered are all inexpensive and plug-n-play modules to sense and control inputs from the physical world. This provides countless possibilities of interacting with sensors, integrating them with the module and the RBPi to obtain unparalleled performance with ease.

For instance, Lime Microsystems and the SEED Studio have a new kit providing everything to start up a Software Defined Radio (SDR) with the RBPi and develop IoT applications for it. The LimeSDR Mini kit targets educational use and is meant for beginners. Lime has optimized the building block for use at 433/868/915 MHz and provides the necessary antennas in the kit. The kit also has an array of sensors from Grove and boards related to output from SEED Studios. The GrovePi+ board offers the computing power for the SDR, and you can use an RBPi 2, 3, or Z.

Magnetic Sheets Prevent Noise from Spreading

Electrical or magnetic noise is a byproduct of electrical activity within an operating device, and it causes several types of nuisance. A device generating a strong electrical or magnetic interference (EMI) can influence a nearby device, making it malfunction or even prevent it from operating at all. The extent to which a device affects another with its electrical or magnetic fields is called its Electromagnetic Compatibility, while the extent to which a device is susceptible to external electrical or magnetic fields is called its Electromagnetic Susceptibility.

Engineers make efficient use of such electromagnetic characteristics of devices. For instance, smartphones and other devices have wireless charging technology and near-field communication. Both make use of electromagnetic fields, the first to charge the device, and the other, allowing communication with nearby devices, both without any physical connection.

The above requires effective shielding and suppression of noise from electronic products. Magnetic sheets offer one such method, with the TDK Corporation offering the latest types of noise suppressing sheets, the IFM10M, a new addition to its Flexield series. TDK claims its new magnetic sheet suppresses noise over a frequency range of 500 KHz to 10 GHz. This is useful for several types of electronic devices, such as industrial terminals, point-of-sale systems, stylus pens, notebooks, tablets, and smartphones.

Featuring a laminated design, the IFM10M series of magnetic sheets consist of a copper-plated layer and a magnetic layer sandwiched together. Although there are several other types of magnetic sheets available in the market, the IFM10M sheets are exceptional as they are only 0.04 mm thick, making them over 60% thinner than their existing counterparts, but offering the same performance. IFM10M sheets are available in sizes of 300×200 mm, with an operating temperature range of -40 to +85°C.

As the IFM10M sheets are so thin, they are well suited for slim products such as stylus pens, notebooks, tablets, and smartphones. Their thin and flexible nature allows installation in dense environments. As the design of electronic devices is making them ever thinner, electronic components are also being mounted in higher densities. The increasing density of packing electronic components together leads to increase in noise emissions from components and cables causing more interference within the device.

By using IFM10M magnetic sheets on power coils, SOCs, and attaching them to the surface of flexible boards and cables, it is possible to reduce the effects of noise emission from one printed board to another.

The new magnetic sheets can improve both electromagnetic compatibility and electromagnetic susceptibility. The noise-absorbing properties of IFM10M reduce the effect of radiated noise as applicable to radiating sources. At the same time, the sheets can also protect components and circuits that are vulnerable to emissions of external noise and thereby reduce their potential impact.

Users can cut the IFM10M magnetic sheets to desired size to fit within available space. They can even shape them as required and install them in very small gaps, as the sheets are very thin and flexible. According to TDK Corporation, the magnetic sheets can improve the sensitivity of receivers for devices using stylus as inputs as these utilize inductive coupling.

High Accuracy Digital Temperature Sensor

Analog Devices is offering a high accuracy digital temperature sensor that covers a wide industrial range. The tiny package also incorporates a humidity sensor. There is no necessity of adding a separate analog to digital converter to this sensor, as the device has one built into it, and provides a high-resolution digital output of 16 bits. With a wide operating voltage range, the device is suitable for industrial, domestic, and commercial use.

The ADT7420UCPZ-R2 from Analog Devices measures temperatures from -40°C to +150°C, while operating from a voltage range of 2.7 to 5.5 V. The device is available in a 4 mm x 4 mm package commonly known as Lead Frame Chip Scale Package (LFCSP). This wire bond plastic encapsulated near chip scale package has a substrate of copper lead frame within a leadless package format. Input/output copper pads are positioned on the perimeter edges of the package.

This allows the user to solder the perimeter pads and the exposed paddle available on the bottom surface of the package to the PCB. The exposed thermal pad on the bottom of the package conducts heat away from the package when it is soldered to the copper layer on the PCB. The thermal and perimeter pads are tin plated to provide good soldering.

Within the ADT7420 is an internal band gap reference, along with a temperature sensor. The 16-bit ADC within the device monitors the temperature and digitizes it to a resolution of 0.0078°C. By default, the ADC resolution is set to 13 bits or 0.0625°C, which should be adequate for most users. However, the user can change the ADC resolution via a programmable mode, to 16 bits. The programmable mode is accessible to the user through an I2C serial interface.

Analog Devices guarantees the ADT7420 will operate reliably when supplied from 2.7 V to 5.5 V. Typical current consumption by the device id 210 µA when operating from a supply voltage of 3.3 V. The user can optionally power down the device to make it enter a shutdown mode where the current consumption is typically 2.0 µA at 3.3 V. There is an additional power saving mode, where the user programs the device to read one sample per second. The temperature drift for ADT7420 is merely 0.0073°C.

The ADT7420 exhibits very high temperature accuracy of ±0.20°C between -10°C and +85°C, when working from a 3.0 V supply. When working from a wider supply voltage of 2.7 to 3.3V, the temperature accuracy of the device is ±0.25°C between -20°C and +105°C. As soon as the device powers up, the first temperature reading is available within 6 ms.

Implementing the ADT7420 is very easy, as it does not need any temperature calibration or correction by the user. The user also does not require any linearity correction for the usable temperature range. The user can program the device to produce an interrupt when it senses the temperature crossing a preset critical temperature.

Applications for the ADT7420 include replacement for RTD and thermistor, and compensation for thermocouple cold junction. Typically, the device is usable in medical equipment, and for industrial control and test, food transport and storage, environmental monitoring and HVAC, and Laser diode temperature control applications.

Tree-Axis High Resolution Digital Accelerometer

Most modern smartphones can sense whether their users are holding them in the portrait or in the landscape position, accordingly adjusting the displayed image. Additionally, while playing games such as Temple Run, the smartphone can respond to tilting by changing certain functions in the game. The smartphone accomplishes this motion sensing as it has an accelerometer IC working inside it.

Apart from smartphones, several other applications make use of accelerometers. For instance, car alarms can be programmed to alert their drivers as soon as they cross a certain speed threshold. Hill Start Aid (HSA) systems depend on accelerometers to alert drivers when their vehicles start climbing a defined slope. Accelerometers tell weighing machines whether a vehicle is properly positioned before starting to take readings. Black boxes or data recorders in airplanes, trains, and other vehicles stop recording when an accelerometer decides there has been a violent incident.

Analog Devices makes ADXL313, one of such versatile digital accelerometers. The device has very high resolution of 13 bits on each of its three axes, and is capable of measuring up to ±4 g, where 1 g is the normal level of acceleration due to gravity at sea level. ASXL313 offers a 16-bit data output in a two’s complement format. The user can access this digital output through either an I2C serial interface, or a 3- or 4-wire serial port interface (SPI).

Being very small, only 5x5x1.45 mm, ADXL313 comes in a lead-free, RoHS compliant, LFCSP package and is qualified for automotive applications with a wide operating temperature range of -40°C to +105°C. The device is capable of surviving shocks up to 10,000 g. ADXL313 can work with a wide supply range of 2.0 to 3.6 V, consuming ultra-low levels of power. At a supply voltage of 3.3 V, the ADXL313 consumes only 30 µA in measurement mode, and only 0.1 µA in its standby mode.

While its embedded FIFO technology minimizes processor load for the host, ADXL313 offers an exemplary noise performance of typically 150 µg/√Hz for its X- and Y-axes, and typically 250 µg/√Hz for its Z-axis. While its user-selectable resolution is limited to a 10-bit resolution for any g value on the low side, its sensitivity is a minimum of 1024 LSB/g for any g range. On the upper side, its resolution scales from 10-bits at ±0.5 g to 13-bits at ±4 g. ADXL313 features a built-in motion detection function for monitoring activity/inactivity.

The ADXL313 3-axis digital accelerometer offers its user several flexible interrupt modes, which the user can map to two interrupt pins. Along with the built-in sensing function, the device can sense the presence or absence of motion, and detect whether the acceleration on any axis is exceeding the user-set level. The user can map these functions on two interrupt output pins, which can alert the controlling micro-controller accordingly.

ADXL313 has an integrated 32-level FIFO register to store data. This minimizes host processor intervention leading to a huge reduction is system power consumption. This low power mode enables intelligent motion-based power management and empowers the device with threshold sensing and active measurements while dissipating extremely low levels of power.

Using Reed Switches as Sensors

Any ordinary electrical switch has two contacts. Push-type switches are spring loaded so that pushing a button brings them together and they spring apart on releasing the button. Rocker switches have mechanical levers that close the contacts when in one position, while in the other position they pull apart.

In reed switches, the two contacts are in the shape of metal reeds, each coated with a metal that does not wear easily. The reeds are made from a ferromagnetic material, so they are easy to magnetize. The entire assembly is hermetically sealed within a thin glass envelope containing a nonreactive gas such as nitrogen. For extra protection, sometimes the glass envelope may have a plastic casing.

The ferromagnetic material making up the reeds is typically a nickel-iron alloy that shows high magnetic permeability but low magnetic retentivity. That means, when brought close to a magnet, it magnetizes the reeds, which come together in contact. On moving the switch away from the magnetic field, the reeds lose their magnetic property and separate. Their movement has high hysteresis, that is to say they close and open slowly and smoothly. The reeds have a flat area where they contact each other, and this helps to extend the life and reliability of the switch.

Although reed switches typically have two ferromagnetic contacts, some variants may have only one ferromagnetic contact, while the other is non-magnetic. Others may have three contacts, with two non-magnetic and the central one as ferromagnetic.

Like ordinary switches, reed switches also come as two major variants—normally open type and normally closed type. This refers to the position of the reeds when there is no magnetic influence on them. Therefore, the normally open type has its reeds separated from each other, and they close when a magnet is brought close enough. The normally closed type of reed switch has its reeds in contact with each other, and they move apart when a magnet is brought close enough.

As the magnet comes close to a normally open reed switch, the two contacts become magnetized as opposite magnetic poles, and they attract each other to close. In this position, the switch can pass an electric current. This magnetizing of the reeds is independent of the pole of the magnet coming close to them. As the magnet moves away, the reeds lose their magnetism, and their stiff and springy nature makes them spring apart in their original position.

Reed switches are very useful as sensors such as for sensing level of liquids. A sealed stem holds the reed switches at different heights. A float containing a permanent magnet rides on the stem, going up and down as the liquid level changes. When the float magnet comes close to one of the reed switches, it snaps close, changing its electrical status that any electronic circuit can sense. Automotive, marine, and industrial applications use reed switches for level sensing.

A float switch in a dishwasher controls the level of water in the machine. The shaft containing the reed switch is positioned at the water fill limit of the pan. As the water rises, so does a float containing the magnet. When the magnet comes close to the reed switch, it closes, and signals the ECU.

How to Keep Your Bearings Running Cool

Electronic gadgets rely on a host of equipment for their creaseless performance. One of them is power generating equipment—spinning generators, motors, and shafts that create and transmit power. In fact rotating machinery is the basis not only of electronic gadgets, but also of modern civilization itself. A wide variety of lubricated and self-lubricating bearings keeps these machines operating smoothly and efficiently. Heat is a major factor affecting bearings, degrading its lubrication and damaging the bearing, ultimately increasing friction and decreasing efficiency.

Normal operations rarely merit concerns over temperature rise of bearings. However, exposure to abnormally high loads and speeds, high ambient temperatures, and hot process fluids can cause problems.

For instance, roller bearings can start to run hot because rolling elements microslip on the races. Another reason is the contact stress generated hysteresis of rolling elements and race materials. Even the sliding between the pilot surfaces or rolling elements and their separator and the sliding between guide flanges and rollers generates heat. Shear and turbulence in the lubricant also generates some heat.

One of the best means of heat control in bearings is by using cooled oil, particularly useful in gas turbines and pumps for hot liquids. Although lubrication needs only a thin film of oil, high flow rates of oil can also help to cool bearings. The common practice is to set the nominal oil level to the center of the bottom ball bearing. This works satisfactorily except for extremely high speeds, when an oil flinger providing a mist of oil becomes necessary. In places where the above cannot be used, heat is removed by convection from the bearing housing to the ambient air.

Thrust bearings are susceptible to the viscosity of the lubricant they use. Viscous friction can cause power loss, which can be substantially reduced by lower lubricant viscosity. However, the best way of keeping thrust bearings cool is increase the volume of oil flowing over each pad segment. Another method often followed by engineers is to directly cool the oil feed or cool the bearing housing from the outside. Using copper plates in place of steel backing also helps to keep bearings cool, as copper conducts heat away better than steel does.

Sleeve or journal bearings have a longer life when running cool. Therefore, it is important to take steps to bring down the operating temperature. Although sleeve bearings also benefit from lower viscosity oil, the cooling effects are somewhat limited. This is because the viscosity of the oil film rises as the overall temperature drops. Nevertheless, low viscous oil helps in cooling sleeve bearings in high-speed machinery.

Engineers strive to maintain an optimal radial bearing clearance as this has a pronounced influence on bearing performance and hence its operating temperature. If normal clearance is small, the sleeve bearing can run hot and the cooler housing can constrain it, leading to a seizure.

Too much clearance can also lead to vibration, unbalance, and other instabilities. To avoid such undue vibration and temperature rise, engineers must follow recommended diametrical clearances.