Essay: Monitoring systems

As man has evolved, so has his inventions. All of these tools, and eventually machines, were created with the goal in mind of making life easier and many of these took the form of improvements to previously invented items. A large part in making improvements to machines is the decrease the time of maintenance as well as increase the time required between maintenance. Over time these improvements had developed from basic upgrades to increase the life of the product and then began to expand exponentially. Maintenance strategies began to be put into place and grew from the bare minimum into the condition monitoring systems that our society has become to rely on without even realizing it in today’s time.

 

These strategies started as just a basic “run-to-failure” technique which basically just ran the equipment until it couldn’t anymore and then the necessary maintenance and/or replacement would be undergone. This technique can prove to be extremely expensive and not very viable. Another strategy used is “preventative maintenance” which can be compared to just using an operating/owner’s manual and following the directions of when to repair/replace certain items. This technique will always be viable in one way or another but in the end, works more efficiently when paired with others. Condition-based maintenance is based on the specific conditions at any given time under normal operating conditions. This started to include internal monitoring programs to check parts throughout the system for maintenance needs based on the current conditions of the particular piece of equipment. This system guarantees parts aren’t being switched/repaired too early or too late with preventative maintenance. These strategies are used in all kinds of mechanical power transmission applications but we will be focusing on the use of condition based monitoring specifically in that of maritime and automobile operations.

There are many monitoring systems throughout your typical automotive or maritime vehicle, however, your typical user has no idea how these systems actually know how to relay the information to the end user. To start off, the monitoring system that seems to be the easiest to explain and most common for people to have an understanding of would be the fuel gauge. Fuel gauges are used in many devices, such as lawnmowers, four-wheelers, automobiles, and even maritime vehicles. The specific unit and type of gauges/sensors may vary from machine to machine, but for the most part the units operate in the same capacity. As most people are aware, a fuel gauge shows how full, or empty, your vehicle is on fuel and once it gets to a certain level, it display’s a “low fuel” light. The way the device knows how much fuel it actually has is actually through simple electricity. In the fuel tank, there is a small floater which is attached to a resistor by a thin metal rod (UnipartCarCareCentres/UCCC). The resistor is powered by the battery and sends an electrical signal to the fuel gauge. As the float drops, the more current is sent to the fuel gauge and the lower the fuel gauge reads to the operator (See Figure 1 below). This “sender” and “gauge” work as one to ensure that the end user is aware of the changing fuel levels of the vehicle. If this device falters and displays either entirely incorrect readings or just one reading all the time, the system must be checked. In order to check the functionality of a fuel gauge system there are multiple methods on how to determine if the sender or gauge are dysfunctional or it’s an outside problem (See Figure 2 below).

Figure 1 (UnipartCarCareCentres/UCCC)

Figure 2 (Falvey)

As for fuel gauges, oil gauges are similar in the way that there are different types of oil gauge monitoring systems but each works in a similar fashion. Typically for oil gauges, a vehicle’s gauge is operated by either a mechanical gauge or an electric gauge. Each accomplishes the same task at hand but there are some pros and cons to each type of gauge.

For a mechanical oil gauge, the scale and needle assembly are connected to the engine’s oilway by an oil connection pipe (typically copper or plastic) with a small bore (around 3mm). The pipe is routed around the engine area in such a way so it couldn’t be damaged because if it was damaged, the engine’s oil would begin to leak. The oil is then fed through the supply pipe up to the scale into a bulb system in the gauge (See Figure 3 below). The oil is fed into the bulb at nearly the same pressure as it had left the engine and because of the pressure the bulb attempts to straighten itself which causes the needle to move around the calibrated scale. Dependent on the pressure received, the more the needle moves, the greater the pressure (How a Car Works). Although mechanical oil gauges aren’t as common as electric gauges and sometimes they tend to cause messy leaks if not properly aligned/assembled, they are often viewed as the more trustworthy gauge.

Figure 3 (How a Car Works)

For an electric oil gauge, the gauge is connected to another assembly by a wire. This assembly is screwed into the engine block and sends a current to the gauge depending on the oil pressure. The oil pressure causes the wiper in the assembly to run up and down a resistance blade which is connected to the return wire to the gauge (See Figure 4 Below). The more this system moves under pressure, the higher the oil pressure. The resistance of this sensor varies with differing oil pressures which then moves the needle of the gauge accordingly. This assembly then passes current through to a coil mounted around the gauge needle which produces a magnetic field that causes the needle to move across the gauges calibrated scale (How a Car Works). Typically, electric gauges are a lot less bulky and tend to be easier to integrate into most modern vehicles.

Figure 4 (How a Car Works)

The last monitoring system that I will be focusing on is the brake wear sensor. As cars are used the brake pads get worn down and eventually need to be changed out. In order to forgo having to constantly check the brake pads manually a system was implemented to constantly be checking to brake pads for its thickness, remaining life-span, and alerting the driver when the brake material is almost gone. The sensor location can vary from vehicle to vehicle depending on the type of brake pads and wheels but typically the sensor is placed at a predetermined location within the brake pad. Once this sensor is activated it notifies the driver that the brake pads need to be replaced. On most vehicles, this means that there is about 100 miles of material left but it should probably still be replaced as soon as possible to avoid any potential wear and tear on your wheels or brakes if the pad gave out any sooner. These sensors are all connected by wires that feed to each of the four wheels and back to the automobile’s computer system (Autos). Once the system registers an “open current” the emergency light will illuminate on the dashboard to notify the driver that they need to be replaced.

Although most people don’t have any idea as to what the term condition monitoring systems are, our lives would be entirely different without them. The raw number of vehicle breakdowns or stranded boats in the middle of bodies of water would skyrocket. As people are starting to grow up in a time where condition monitoring is expected, it’s being taken for granted since that’s all they’ve ever seen. Condition monitoring is the taking over the mechanical power transmission world when it comes to maintenance and is over getting better over time. Without devices like the fuel gauge system, oil gauge system, or even the brake pad monitoring system, society today would be lost. I don’t see condition monitoring going away anytime soon, and if anything will only improve to further increase the time between maintenance as well as further develop safer modes of transportation and manufacturing within the mechanical power transmission world.