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Auxiliary Engine


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Auxiliary Engine


Cat marine auxiliary engines are the solution for unique generator set applications requiring a custom approach. Additionally, the are perfectly engineered for electrically driven pumps, winches, conveyors and thrusters.


An auxiliary power unit (APU) is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft and naval ships as well as some large land vehicles. Aircraft APUs generally produce 115 V AC voltage at 400 Hz (rather than 50/60 Hz in mains supply), to run the electrical systems of the aircraft; others can produce 28 V DC voltage.[1] APUs can provide power through single or three-phase systems.


During World War I, the British Coastal class blimps, one of several types of airship operated by the Royal Navy, carried a 1.75 horsepower (1.30 kW) ABC auxiliary engine. These powered a generator for the craft's radio transmitter and, in an emergency, could power an auxiliary air blower.[Note 1][2] One of the first military fixed-wing aircraft to use an APU was the British, World War 1, Supermarine Nighthawk, an anti-Zeppelin night fighter.[3]


The power section is the gas-generator portion of the engine and produces all the shaft power for the APU.[10] In this section of the engine, air and fuel are mixed, compressed and ignited to create hot and expanding gases. This gas is highly energetic and is used to spin the turbine, which in turn powers other sections of the engine, such as auxiliary gearboxes, pumps, electrical generators, and in the case of a turbo fan engine, the main fan [11]


The gearbox transfers power from the main shaft of the engine to an oil-cooled generator for electrical power. Within the gearbox, power is also transferred to engine accessories such as the fuel control unit, the lubrication module, and cooling fan. There is also a starter motor connected through the gear train to perform the starting function of the APU. Some APU designs use a combination starter/generator for APU starting and electrical power generation to reduce complexity.


The Space Shuttle APUs provided hydraulic pressure. The Space Shuttle had three redundant APUs, powered by hydrazine fuel. They were only powered up for ascent, re-entry, and landing. During ascent, the APUs provided hydraulic power for gimballing of the Shuttle's three engines and control of their large valves, and for movement of the control surfaces. During landing, they moved the control surfaces, lowered the wheels, and powered the brakes and nose-wheel steering. Landing could be accomplished with only one APU working.[20] In the early years of the Shuttle there were problems with APU reliability, with malfunctions on three of the first nine Shuttle missions.[Note 2]


APUs are fitted to some tanks to provide electrical power without the high fuel consumption and large infrared signature of the main engine. As early as World War II, the American M4 Sherman had a small, piston-engine powered APU for charging the tank's batteries, a feature the Soviet-produced T-34 tank did not have.[25]


On some older diesel engined-equipment, a small gasoline engine (often called a "pony engine") was used instead of an electric motor to start the main engine. The exhaust path of the pony engine was typically arranged so as to warm the intake manifold of the diesel, to ease starting in colder weather. These were primarily used on large pieces of construction equipment.[27][28]


Within a single OS process, the work performed during warmup can be shared by specifying an explicit engine.This requires language implementations to disable context-related optimizations to avoid deoptimizations between contexts that share code.Auxiliary engine caching builds upon the mechanism for disabling context-related optimizations and adds the capability to persist an engine with ASTs and optimized machine code to disk.This way, the work performed during warmup can be significantly reduced in the first application context of a new process.


We use the SVM auxiliary image feature to persist and load the necessary data structures to the disk.Persisting the image can take significant time as compilation needs to be performed.However, loading is designed to be as fast as possible, typically almost instantaneous.This reduces the warmup time of an application significantly.


Starting from a GraalVM EE installation, you first need to (re)build an image with auxiliary engine caching capabilities.For example, one can rebuild the JavaScript image by adding the auxiliary engine cache feature:


The --macro argument value depends on the guest languageBy default, auxiliary images of up to 1GB are possible.The maximum size can be increased or decreased as needed.The amount of reserved bytes does not actually impact the memory consumed by the application.In future versions, the auxiliary engine cache will be enabled by default when the --macro:js-launcher macro is used.


There are generally no restrictions on the kind of applications that can be persisted.If the language supports a shared context policy, auxiliary engine caching should work.If the language does not support it, then no data will be persisted.


There can only be one active auxiliary image per native-image isolate.Trying to load multiple auxiliary images at the same time will fail.Currently, auxiliary images can also not be unloaded, but it is planned to lift this restriction in the future.


All data that is persisted to disk represents code only and no application context-specific data like global variables.However, profiled ASTs and code may contain artifacts of the optimizations performed in a Truffle AST.For example, it is possible that runtime strings are used for optimizations and therefore persisted to an engine image.


It can be useful to debug language implementation issues related to auxiliary image on HotSpot.On GraalVM EE in JVM mode, we have additional options that can be used to help debug issues with this feature:Since storing partial heaps on HotSpot is not supported, these debug features do not work on HotSpot.


Debugging the loading of persisted engines is more difficult as writing an engine to disk is not supported on HotSpot.However, it is possible to use the polyglot embedding API to simulate this use-case in a unit test.See the com.oracle.truffle.enterprise.test.DebugEngineCacheTest class as an example.


An investigation by The Swedish Club into auxiliary engine damage has revealed that the majority of all damage takes place immediately after maintenance work. A key finding is that 55% of casualties occur within only 10% of the time between overhaul (TBO), corresponding to the first 1,000 hours or so of operation after overhaul. In most cases the damage occurs only a few hours after start up.


The report, Auxiliary Engine Damage, also finds that container vessels have a significantly higher claims frequency due to the larger number of installed engines on these vessels. In addition these engines have considerable output, leading to higher repair costs compared with other vessels.


We see incorrect maintenance and wrongful repair in all too many cases, and poor lubrication management is also a major contributing factor to auxiliary engine break downs. With an average repair cost of more than USD 345,000, we cannot emphasise enough the principle that prevention is better than cure.


We can outfit your carrier with your choice of either a 200 HP C6.6 CAT engine or similar John Deere 6 cylinder engine for your machine. Custom piping on the boom and controls in the cab create what is called a Closed Loop hydraulic system. This frees up your carrier to do what it does best and full power and separate hydraulic system to run your mower head, stump grinder, or other attachment.


The optional auxiliary engines are not needed, but for those that make forestry and land clearing their business, the auxiliary engines drastically speed up your production time and the size material you can clear, paying for themselves in very short order.


The auxiliary engines are used for electrical power production on board and can represent up to 15% of the total fuel consumption for a vessel with diesel mechanical. There are many different engine configurations, with normally 2 or 3 auxiliary engines on a diesel-mechanical vessel, and 4 to 6 auxiliary engines on diesel-electric vessels. The engine performance and efficiency aspects of the auxiliaries are quite similar to the large 2-stroke propulsion engines as they are often more efficient at higher loads.


The key of this measure relates to the fact that many vessels run more auxiliary engines simultaneously than are actually needed regarding power consumption vs. production-basis during normal deep sea transit. This is amongst others related to risk aversion of black-out, i.e. your only running auxiliary engine dropping out. The safety margin against black-out from running more than one engine can, however, often be reasoned. During manoeuvring or other similar operations losing power production can be very critical, but during deep sea transit in calm weather it is typically not critical to experience a black-out. In addition to risk aversion for black-out, general wear and tear of the auxiliary does tend to bring down their rating (maximum kW production), meaning that the assumed load level is in fact higher. This is quite normal and should easily be fixed via e.g. overhaul of the turbochargers.


In order to minimize the fuel consumption on the auxiliaries through increasing the average engine load, the number of auxiliary engines running must be minimized at all times. This could be included in a ship specific auxiliary engine operation guideline. A guide for the number of engines running could be developed based on the possibility to measure the kWh produced and compared with the operational mode. Lowering the number of auxiliary engines also reduces the engine hours, the rate of wear and tear per hour, lubrication oil consumption and consequently work needed to do maintenance. The average engine load is as such on its own a good performance indicator to work from, but it must not contribute to compromising safety, and a risk based approach is as such advised. 59ce067264






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