Apu installation

Apu installation DEFAULT

Auxiliary power unit

Not to be confused with AMD Accelerated Processing Unit.

See also: Uninterruptible power supply

A Honeywell GTCP36 APU mounted under the tail of a business jet
APU exhaust at the tail end of a Boeing 747-200

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 VAC 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.

Transport aircraft[edit]


The intake diverter of the Jumo 004, with pull-start handle for Riedel APU and its sparkplug access ports
The Riedel2-stroke engine used as the pioneering example of an APU, to turn over the central shaft of both World War II-era German BMW 003and Junkers Jumo 004jet engines.
The Riedel APU installed on a preserved BMW 003 jet engine, with what appears to be an electric starter for the Riedel APU.

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]

During World War II, a number of large American military aircraft were fitted with APUs. These were typically known as putt–putts, even in official training documents. The putt-putt on the B-29 Superfortress bomber was fitted in the unpressurised section at the rear of the aircraft. Various models of four-stroke, Flat-twin or V-twin engines were used. The 7 horsepower (5.2 kW) engine drove a P2, DC generator, rated 28.5 Volts and 200 Amps (several of the same P2 generators, driven by the main engines, were the B-29's DC power source in flight). The putt-putt provided power for starting the main engines and was used after take-off to a height of 10,000 feet (3,000 m). The putt-putt was restarted when the B-29 was descending to land.[4]

Some models of the B-24 Liberator had a putt–putt fitted at the front of the aircraft, inside the nose-wheel compartment.[5] Some models of the Douglas C-47 Skytrain transport aircraft carried a putt-putt under the cockpit floor.[6]

As mechanical "startup" APUs for jet engines[edit]

The first German jet engines built during the Second World War used a mechanical APU starting system designed by the German engineer Norbert Riedel. It consisted of a 10 horsepower (7.5 kW) two-strokeflat engine, which for the Junkers Jumo 004 design was hidden in the intake diverter, essentially functioning as a pioneering example of an auxiliary power unit for starting a jet engine. A hole in the extreme nose of the diverter contained a manual pull-handle which started the piston engine, which in turn rotated the compressor. Two spark plug access ports existed in the Jumo 004's intake diverter to service the Riedel unit's cylinders in situ, for maintenance purposes. Two small "premix" tanks for the Riedel's petrol/oil fuel were fitted in the annular intake. The engine was considered an extreme short stroke (bore / stroke: 70 mm / 35 mm = 2:1) design so it could fit within the intake diverter of jet engines like the Jumo 004. For reduction it had an integrated planetary gear. It was produced by Victoria in Nuremberg and served as a mechanical APU-style starter for all three German jet engine designs to have made it to at least the prototype stage before May 1945 — the Junkers Jumo 004, the BMW 003 (which uniquely appears to use an electric starter for the Riedel APU),[7] and the prototypes (19 built) of the more advanced Heinkel HeS 011 engine, which mounted it just above the intake passage in the Heinkel-crafted sheetmetal of the engine nacelle nose.[8]

The Boeing 727 in 1963 was the first jetliner to feature a gas turbine APU, allowing it to operate at smaller airports, independent from ground facilities. The APU can be identified on many modern airliners by an exhaust pipe at the aircraft's tail.[9]


A typical gas-turbine APU for commercial transport aircraft comprises three main sections:

Power section[edit]

The power section is the gas-generator portion of the engine and produces all the shaft power for the APU.[10]

Load compressor section[edit]

The load compressor is generally a shaft-mounted compressor that provides pneumatic power for the aircraft, though some APUs extract bleed air from the power section compressor. There are two actuated devices: the inlet guide vanes that regulate airflow to the load compressor and the surge control valve that maintains stable or surge-free operation of the turbo machine.[10]

Gearbox section[edit]

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.

On the Boeing 787 more-electric aircraft, the APU delivers only electricity to the aircraft. The absence of a pneumatic system simplifies the design, but high demand for electricity requires heavier generators.[11][12]

Onboard solid oxide fuel cell (SOFC) APUs are being researched.[13]


On June 4, 2018, Boeing and Safran announced their 50-50 partnership to design, build and service APUs after regulatory and antitrust clearance in the second half of 2018.[14] Boeing produced several hundred T50/T60 small turboshafts and their derivatives in the early 1960s. Safran produces helicopters and business jets APUs but stopped the large APUs since Labinal exited the APIC joint venture with Sundstrand in 1996.[15]

This could threaten the dominance of Honeywell and United Technologies.[16] Honeywell has a 65% share of the mainliner APU market and is the sole supplier for the A350, the B777 and all single-aisles: the B737 MAX, Airbus A220 (formerly Bombardier CSeries), Comac C919, Irkut MC-21 and A320neo since Airbus eliminated the P&WC APS3200 option. P&WC claims the remaining 35% with the A380, B787 and B747-8.[15]

It should take at least a decade for the Boeing/Safran JV to reach $100 million in service revenue. The 2017 market for production was worth $800 million (88% civil and 12% military), while the MRO market was worth $2.4 billion, spread equally between civil and military.[17]


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.[18] 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]

Armored vehicles[edit]

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.[23]

Commercial vehicles[edit]

A refrigerated or frozen food semi trailer or train car may be equipped with an independent APU and fuel tank to maintain low temperatures while in transit, without the need for an external transport-supplied power source.[citation needed][24]

On some older diesel engines, an APU was used instead of an electric motor to start the main engine. These were primarily used on large pieces of construction equipment.[25][26]

Fuel cells[edit]

Main article: Fuel cell auxiliary power unit

In recent years, truck and fuel cell manufacturers have teamed up to create, test and demonstrate a fuel cell APU that eliminates nearly all emissions[27] and uses diesel fuel more efficiently.[28] In 2008, a DOE sponsored partnership between Delphi Electronics and Peterbilt demonstrated that a fuel cell could provide power to the electronics and air conditioning of a Peterbilt Model 386 under simulated "idling" conditions for ten hours.[29] Delphi has said the 5 kW system for Class 8 trucks will be released in 2012,[needs update] at an $8000–9000 price tag that would be competitive with other "midrange" two-cylinder diesel APUs, should they be able to meet those deadlines and cost estimates.[28]

See also[edit]


  1. ^A continuous supply of pressurized air was needed to keep the airship's Ballonets inflated, and so maintain the structure of the gasbag. In normal flight, this was collected from the propeller slipstream by an air scoop.
  2. ^Early Shuttle APU malfunctions:
    • STS-2 (November 1981): During a launchpad hold, high oil pressures were discovered in two of the three APUs. The gear boxes needed to be flushed and filters replaced, forcing the launch to be rescheduled.[19]
    • STS-3 (March 1982): One APU overheated during ascent and had to be shut down, although it later functioned properly during re-entry and landing.[20][21]
    • STS-9 (November–December 1983): During landing, two of the three APUs caught fire.[22]


  1. ^"400 Hz Electrical Systems". Ask a Rocket Scientist. Aerospaceweb.org.
  2. ^Abbott, Patrick (1989). The British Airship at War, 1914–1918. Terence Dalton. p. 57. ISBN .
  3. ^Andrews and Morgan 1987, p. 21.
  4. ^Wolf, William (2005). Boeing B-29 Superfortress: the ultimate look : from drawing board to VJ-Day. Schiffer. p. 205. ISBN .
  5. ^Livingstone, Bob (1998). Under the Southern Cross: The B-24 Liberator in the South Pacific. Turner Publishing Company. p. 162. ISBN .
  6. ^Ethell, Jeffrey; Downie, Don (2004). Flying the Hump: In Original World War II Color. Zenith Imprint. p. 84. ISBN .
  7. ^Schulte, Rudolph C. (1946). "Design Analysis of BMW 003 Turbojet - "Starting the Engine"". legendsintheirowntime.com. United States Army Air Force - Turbojet and Gus Turbine Developments, HQ, AAF. Retrieved September 3, 2016.
  8. ^Gunston 1997, p. 141.
  9. ^Vanhoenacker, Mark (5 February 2015). "What Is That Hole in the Tail of an Airplane?". Slate. Retrieved 20 October 2016.
  10. ^ ab"The APU and its benefits | AERTEC Solutions". www.aertecsolutions.com. Retrieved 2018-06-20.
  11. ^Sinnet, Mike (2007). "Saving Fuel and enhancing operational efficiencies"(PDF). Boeing. Retrieved January 17, 2013.
  12. ^Ogando, Joseph, ed. (June 4, 2007). "Boeing's 'More Electric' 787 Dreamliner Spurs Engine Evolution: On the 787, Boeing eliminated bleed air and relied heavily on electric starter generators". Design News. Archived from the original on April 6, 2012. Retrieved September 9, 2011.
  13. ^Spenser, Jay (July 2004). "Fuel cells in the air". Boeing Frontiers. 3 (3).
  14. ^Safran, Boeing (June 4, 2018). "Boeing, Safran Agree to Design, Build and Service Auxiliary Power Units" (Press release).
  15. ^ abStephen Trimble (June 5, 2018). "How will Boeing-Safran venture shake up APUs?". Flightglobal.
  16. ^Stephen Trimble (June 4, 2018). "Boeing and Safran partner to disrupt APU market". Flightglobal.
  17. ^Kevin Michaels (Jun 27, 2018). "Opinion: Why Is Boeing Diving Into APU Production?". Aviation Week & Space Technology.
  18. ^"Hydraulic System". spaceflight.nasa.gov. NASA. Archived from the original on 2 June 2001. Retrieved 8 February 2016.
  19. ^"Space Shuttle Mission Archives STS-2". www.nasa.gov. NASA. Retrieved 18 February 2016.
  20. ^"Space Shuttle Mission Archives STS-3". www.nasa.gov. NASA. Retrieved 18 February 2016.
  21. ^Lousma, Jack R. (15 March 2010). "Jack R. Lousma Edited Oral History Transcript". NASA Johnson Space Center Oral History Project (Interview). Interviewed by Ross-Nazzal, Jennifer. Retrieved 18 February 2016.
  22. ^"Space Shuttle Mission Archives STS-9". www.nasa.gov. NASA. Retrieved 18 February 2016.
  23. ^Loza, Dimitri (September 21, 2010). "IRemember.ru WW II Memoirs". iremember.ru/en. IRemember. Retrieved June 13, 2017.
  24. ^"Vehicle weight exemptions for APUs".
  25. ^Orlemann, Eric. Caterpillar Chronicle : History of the Greatest Earthmovers. p. 35. ISBN .
  26. ^"Willard v. Caterpillar, Inc. (1995)". Justia Law. Retrieved 13 December 2016.
  27. ^Broderick, Christie-Joy; Timothy Lipman; Mohammad Farshchi; Nicholas Lutsey; Harry Dwyer; Daniel Sperling; William Gouse; Bruce Harris; Foy King (2002). "Evaluation of Fuel Cell auxiliary Power Units for Heavy-Duty Diesel Trucks"(PDF). Transportation Research Part D. Elsevier Sciences Ltd. pp. 303–315. Archived from the original(PDF) on 2012-04-03. Retrieved 2011-09-27.
  28. ^ abWeissler, Paul (2010-05-12). "Delphi truck fuel-cell APU to hit road in 2012". Vehicle Electrification. Retrieved 2011-09-27.
  29. ^Jacobs, Mike (2009-03-19). "Solid Oxide Fuel Cell Successfully Powers Truck Cab and Sleeper in DOE-Sponsored Test". NETL: News Release. National Energy Technology Laboratory. Retrieved 2011-09-27.

External links[edit]

Sours: https://en.wikipedia.org/wiki/Auxiliary_power_unit

Aircraft APU Powerplant Removal and Installation

2. Remove lower support shroud.
3. Disconnect APU harness, APU starter motor, and APU generator plugs from receptacles in upper shroud.
4. Disconnect APU generator control plug from receptacle in upper shroud.
5. Disconnect exhaust gas temperature (EGT) indicating system plug from receptacle in upper shroud.

6. Disconnect bleed load control air line from fitting in upper shroud.
7. Disconnect fuel hose from elbow on low pressure fuel filter. Collect dripping fuel in a suitable container.
8. Disconnect fire detection sensor element plug from receptacle in upper shroud.
9. Disconnect APU to upper shroud bonding jumper.
10. Remove clamp attaching bleed air duct coupling to turbine plenum bleed air flange.
11. Push bleed air duct coupling outboard as far as it will go.
12. Move compressor air inlet duct lock handle outboard until heel of cam is free from spring arm.
13. Rotate compressor plenum downward so that compressor air inlet opening in plenum no longer matches air inlet duct in upper shroud.
14. Install hoist assemblies to brackets in APU compartment with pins.
15. When using F80002 cradle, insert tubes in cradle base and secure in place with pins.
16. Attach hoist cables to cradle assembly tubes with pins.
17. Install cradle base on APU powerplant and secure in place with pins.
18. Pull hoist cables taut to remove load from APU engine mounts.
19. Remove nuts, washers, and bolt fastening mount caps to engine mount brackets. Do not remove cap and mount bracket hinge bolts. Open mount caps.
20. Lower powerplant slowly. Guide unit to clear bleed air duct coupling, fuel line, and airplane structure.
21. After the unit is set on transportation dolly, slacken hoist cables.
22. Disconnect hoist cables from tubes by removing pins.

Install APU Powerplant

1. Position APU powerplant, installed on a cradle base, directly under APU compartment.
2. Connect hoist cables to tubes with pins.
3. Rotate compressor plenum air inlet opening down. Slowly raise APU powerplant. Guide unit to clear airplane structure.
4. With the APU in place, make sure the seal of the cooling air inlet duct is touching the cooling fan flanges.
5. Close mount caps and install bolts, washers, and nuts. Tighten nuts to a torque range of 30 to 40 poundinches.
6. Rotate compressor plenum to match compressor air inlet opening in plenum with air inlet duct in upper shroud.
7. Move compressor air inlet duct lock handle inboard until heel of cam falls behind spring arm. Install locking screws and two nuts to secure locking handle.
8. Slacken hoist cables and disconnect cables from tubes by removing pins.
9. Remove pins securing cradle base to APU powerplant and remove cradle.
10. Remove pins securing hoist to brackets in APU compartment and remove hoists.
11. Slide bleed air duct coupling inboard as far as it will go.
12. Install clamp attaching bleed air duct coupling to turbine plenum bleed air flange.Tighten clampcoupling nut to a torque range of 45 to 55 pound-inches.
13. Connect fuel hose to elbow on low pressure fuel filter.
14. Connect fire detection sensor element plug to receptacle on upper shroud and safety wire.
15. Connect bleed load control air line to fitting in upper shroud.
16. Connect EGT indicating system plug to receptacle in upper shroud and safety wire.
17. Connect APU generator control plug to receptacle in upper shroud and safety wire.
18. Connect APU harness, APU starter motor, and APU generator plugs to receptacles in upper shroud and safety wire connectors.
19. Connect APU to upper shroud bonding jumper.
20. Depreserve, or purge, the fuel system by motoring.


General Procedures for Engine Removal and Installation
Turbofan Powerplant QECA Removal
Installation of Turbofan Engines
Rigging, Inspections, and Adjustments
Turboprop Powerplant Removal and InstallationSours: https://www.aircraftsystemstech.com/p/turbine-engine-powerplant-removal-and_14.html
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The unit has a main engine and generator (left) and a climate control unit (right), as well as a condenser unit that has already been unpacked.

Overnight idling may be part and parcel of the trucker’s life, but that is changing fast. Aside from the environmental issues, your truck’s engine is optimized for the hard work it does hour after hour out on the road, but at idle it takes in as much as 10 times the air needed for combustion. This extra air chills the engine parts and oil, creating unnecessary wear. It also steals most of the heat and power created.

Using a small engine to do the same work of cooling the cab, charging the batteries and, in most cases, providing heat in winter means far less fuel consumption than idling the main engine. The small, two-cylinder engine typically used will be running hot enough to maintain efficient and complete combustion, and its tiny pistons and crankshaft will produce only minimal friction while giving you more than enough heat, electricity and air-conditioning. An auxiliary power unit or genset will use about 0.2 gallons per hour vs. a full gallon an hour for the diesel.

Because of all the fuel consumed, and because injection pressures and air motion and pressure within the cylinder of any diesel drop way down at idle, all but the latest truck engines will crank out high emissions when sitting there idling. Even 2007 engines will be far dirtier than an emissions-certified APU or genset. That’s why idling the main engine is prohibited in more and more areas.

Every high-quality APU or genset arrangement on the market will cool and heat the cab, charge the batteries, give you what you need for running your personal appliances and keep the engine warm, depending upon your exact needs. While doing all that, it will greatly extend the life of your main diesel engine and significantly extend its oil change intervals.

Choosing your APU
There is an amazing variety of APU and genset design. Gensets normally have a large AC generator that produces 110-120-volt, 60-cycle house current and use that current to operate everything connected to the unit. APUs often have a large AC generator and may also have a 12-volt alternator. Some drive an electrical, “hermetic” A/C compressor, but many drive an automotive-style A/C compressor directly off the APU engine’s flywheel. So, picking an APU is a matter of individual philosophy and choice for the same reason that each manufacturer of heavy-duty diesels has its devoted customers. Each type of design has its advantages.

APUs are integrated into the truck in various ways. For example, many interconnect with the truck engine’s cooling system. That way, the APU engine’s heat, which is normally just thrown away, can be used to keep the diesel warm overnight. When integrated in this way, the truck diesel will also keep the APU engine hot so that, when you stop, you’ll be able to start it up easily even if running in Minnesota in January.

Nearly all APUs and gensets use the truck batteries for starting, which not only provides excess cranking power but an easy path for battery charging current coming back from the APU. They also use one of the truck’s fuel tanks for their fuel.

For example, Thermo King’s TriPac combines a small Thermo King diesel, inter-connected with the truck cooling system, with a belt-driven A/C compressor, a 65-amp, 12-volt DC alternator, and a fuel-fired heater that heats the air in the cab and sleeper. If the user wants power for in-cab appliances, an optional 12-volt DC to 120-volt AC inverter is available. Thermo King says the fuel-fired heater produces fewer emissions and uses less fuel to heat the cab than any other setup. The Tri-Pac’s A/C evaporator and blower are contained in a compact unit normally mounted under the bunk.

Such a unit could be left shut down for most of the night in winter and then started in the morning an hour before departure to charge the batteries and warm the main engine.

Carrier’s ComfortPro unit has both a 4,000-watt, 120-volt AC generator and a 60-amp DC alternator. The main generator provides electric resistance heat to the cab in winter, while using the waste heat generated to warm the diesel via the inter-connected APU and engine cooling systems. Like all high-quality arrangements, it has its own radiator and thermostat because the amount of heat its engine produces is normally more than the truck’s cooling system can throw off without the fan and water pump operating. (An exception to this rule is the unusual Willis APU, which drives the truck engine fan with its own electric motor. It thus uses the truck’s radiator to cool the APU engine and the truck’s A/C condenser to throw off the heat generated by its own A/C compressor.)

The ComfortPro provides air-conditioning electrically via a hermetic A/C compressor powered by the large generator on the APU. The electric resistance heaters, hermetic compressor, and high capacity blower are all contained in a unit typically mounted in one of the cab’s side storage compartments. The hermetic compressor retains the advantage of having no belt drive or shaft seal, as well as soldered connections, reducing related maintenance as well as refrigerant leak points.

The RigMaster APU (virtually a genset) minimizes integration of the APU and truck systems to help ensure reliability, according to the company’s marketing and communications manager, Amy Egerter. Evan Gaffney, who is in charge of the company’s educational development and training, says the unit’s 6,000-watt, 120-volt generator heats the engine via a block heater so there is no risk of an APU-related engine coolant leak.

The high-capacity AC generator lets the driver keep the engine warm and run his microwave oven and other such accessories at the same time. APU engine waste heat is used to heat the cab via a heater core installed in the same Rigmaster unit that contains the blower motor and A/C evaporator, thus making use of APU engine waste heat without tapping into the truck cooling system. An electronically controlled valve stops and starts water flow from the APU engine to maintain cab and sleeper temperature.

Gaffney says RigMaster chose a belt-driven, automotive-style A/C compressor for its separate cab cooling unit because these units take up much less space and weigh less than a hermetic unit. The goal, says Egerter, is to minimize the unit’s effect on available storage space in the cab.

The hermetic unit is considered supreme among A/C technicians for its reduced maintenance and long service life. However, the automotive-style compressor’s advantage is that it lends itself to simple do-it-yourself replacement if it ever fails, provided you have the refrigerant removal and charging tasks performed by a licensed technician. A hermetic unit’s lines must be soldered in a skillful manner.

You should choose the unit that you feel will be most reliable and efficient, depending on the way you use your vehicle. Integration of APU and truck systems always carries a small risk of mechanical failure, hence the decision of many APU makers to provide completely separate cab A/C systems. On the other hand, integration always saves weight, complexity and cost. Features such as APU and engine coolant interconnections that include high-quality shutoff valves may allow for integration with confidence.

“Poor installation has a large effect on the operation of the unit,” says RigMaster’s Egerter. It’s clear that 95 percent or more of APU reliability problems are due in large part to poor installation. Performance can also be affected, a theme echoed by every manufacturer. In fact, every single manufacturer we spoke to trains its technicians and certifies them prior to allowing them to do an install.

The problem, according to technicians Mark Loring and Will Reynolds of Barr International, in Salisbury, Md., is that the job is extremely complex. Installations go much better after you have had experience and learned from your mis-steps. Also, since every truck is different, every installation is different. Much of the time and effort involve carefully planning the locations of the various components and the routing of ducting and wiring.

A ComfortPro installation Loring and Reynolds did recently took almost two full days with both highly experienced techs working full-time. They had had Carrier training and this was the second one they had performed.

Unfortunately, few manufacturers will allow you to install your own unit without voiding the warranty. They have learned from experience that if you don’t have a great deal of training and experience, you’ll fail to get everything right, resulting in problems not covered under the unit’s warranty.

Rich Barr, marketing manager at Barr International, says that, in spite of the work involved, the installation involves only about 15 percent of the total cost of the unit. He priced the installation mentioned above based on the belief that his technicians would be able to do the job faster and faster as they gain experience. Thermo King’s Tom Kampf (product manager, APU business) says the critical issue is certification. Thermo King will not put a warranty on a unit unless they have certified the installer. Kampf did allow, however, for the possibility of a one- or two-truck operator becoming certified.

But Kampf says a TriPac takes about a full day to install, depending on the truck’s design. Getting certified would at least double that time. You might well be able to make more money by operating for those two days than you’d save by doing the install yourself, anyway. You also need to realize that the refrigeration part of the air-conditioning system needs to be evacuated (to remove moisture) and charged with refrigerant by a licensed technician using specialized tools. Unless you have these tools and are certified, you need to get this part of the job done by your seller’s technicians anyway.

RigMaster’s Gaffney opened up a third possibility. Work with your dealer and get their guidance and advice. Do much of the work yourself, but bring the unit to the dealer for evacuation and recharge of the refrigerant system. Then pay a certified technician for the time necessary to inspect and approve the installation. If you feel doing an installation yourself could actually be economical, we suggest you discuss such an approach prior to purchasing a unit to see whether or not your dealer and the manufacturer will work with you on this basis.

Even if you don’t install the unit yourself, you should be closely involved with the process. As the RigMaster installation manual says, “Poor placement of the APU will have a negative impact on the performance and accessibility of the unit. Remember that the best location involves practicality, serviceability and aesthetics.”

It goes on to say, “Remember when choosing a location that the harder it is to access the unit, the more difficult it will be to service.” If the unit’s hard to get at, service won’t be done as often, especially when hired drivers are involved. Be at the shop during the early stages of installation so the location of the engine and generator unit will be the one you prefer for easy access where you park. You will also want to influence the location of the unit that carries the A/C evaporator, heating element, and blower – you don’t want them taking your most valued storage space.

Witnessing an Installation
Barr International’s Rich Barr invited us to witness the installation of a ComfortPro unit in their shop as technicians Reynolds and Loring worked. The ComfortPro includes three major components: the engine and generator and their housing; the climate control unit, including the evaporator, fan, and resistance heating mechanism, and its housing; and the condensing unit. They installed the ComfortPro on an International 9500i tractor with sleeper.

Here are just a few highlights of the two-day installation process:
Fig. 1. The unit has a main engine and generator (left) and a climate control unit (right), as well as a condenser unit that has already been unpacked.

Fig. 2. The first step was preparation of the vehicle. The truck had had a fuel-fired heater that became unnecessary once the Carrier unit’s electric resistance heaters were installed. This was removed and Reynolds repaired the hole in one panel by pop riveting in a new piece of sheet metal, shown here being cut to size. He also replaced and painted an entire new panel to get rid of a second hole.

Fig. 3. Careful planning led to a decision to mount the main unit behind the left-hand fuel tank and the climate control unit in the storage compartment nearby. A template was used to drill holes for mounting the climate control unit on the floor of the storage compartment. Insulation was then cut so the mounting screws could be installed.

Fig. 4. Here, the climate control unit is being put into position.

Fig. 5. Drilling holes for the flexible ducts to pass through requires the use of a saw of the right diameter.

Fig. 6. The left-side cab mount huck bolts, whose threads stuck out of the frame, had to be drilled out and replaced with normal bolts turned in the other direction so just the bolt heads would be showing. This was done for clearance. The area was painted once the new bolts were in place.

Fig. 7. The main unit was lifted with a ceiling hoist onto a floor jack for transport to where it would be mounted on the frame rail.

Fig. 8. The unit was suspended by the floor jack as self-locking nuts and bolts were used to attach it. This was done with special slotted fittings that slide over the top and bottom horizontal sections of the frame rail. The nuts were then torqued to 100 lb.-ft.

Fig. 9. The three ducts that carry conditioned air into the sleeper were routed under the bunk. Note that ties are used to fasten them securely in place. The technicians used hundreds of them to secure all wiring and hoses to prevent chafing.

Fig. 10. The condenser unit was mounted on back of the rear sleeper wall, not far from the climate control unit. It has slotted mounting holes so it can be tilted slightly in either direction for leveling. After drilling mounting holes using it as a template and installing the mounting bolts loosely, its position was adjusted with a level and the mounting bolts finally tightened.

Fig. 11. A high quality installation demands purchase and assembly of tees with effective shutoff valves so the APU can be teed into the engine cooling system at the heater hoses yet isolated in case it develops a leak.

Once the unit is installed, says Thermo King’s Kampf, get into the habit of using it every time you’re shut down. “Old idling habits die hard,” he reminds us. He also recommends opting for such devices as the auto start switch offered with the TriPac. Such effective controls help you to get the most for your money by maximizing use of the unit.

For more information:
Carrier ComfortPro

Rigmaster Power Corp.

Thermo King TriPac

Willis APU

Barr International

Sours: https://www.overdriveonline.com/business/article/14880229/abcs-of-apus

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I have never seen such frosts in my memory. Our local basements could not withstand such frosts, and my friend Martha and I moved for a while to the warm and. Comfortable basements of a neighboring house.

How to Install APU TriPac Evolutionin a Volvo Truck # TK Boys Canada - Tagalog

He began to lick. So. Yes. Mmm. Lick her.

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Where do they come from. What do you think, am I crippled. There are more than enough people who want to, just whistle.

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