BeauK Members 2 posts Report post Posted January 10, 2013 I am having the same problem with my 99 Fleetwood Discovery, can you tell me what control module and where it is located. Air compressors are generally powered directly by the vehicles engine or by using belts and pulleys and can be mounted either directly on the engine or by brackets and fasteners. Primary air can also be manually supplied to the trailer by means of a hand valve, (11) usually located on or near the steering column. The dual foot control or treadle valve applies air to both the primary and secondary braking systems in response to the drivers foot pressure. Figure 7. Running multiple air compressors at partial loading is very inefficient. Reservoirs, three per tractor and, usually, two per trailer, store the compressed air until it is needed to actuate the brakes. These are required by law if the coach is not equipped with a wet tank. Normal air brake system pressure range is around 690 to 828 kPa (100 to 120 psi). The control system FMCA members have access to exclusive articles and RV tips, Compressed air should not be the default choice always look for alternatives. Copyright American Institute of Chemical Engineers. Some of the spilled sulfuric acid flowed into a nearby river, causing environmental damage. Drain valves are on each tank. One-Way . Secondary storage may also be needed throughout the plant, as well as at some high-demand locations. An air compressor increases the pressure of inlet air by reducing its volume. At one plant, a compressed air system leak test during a shutdown revealed that 450 horsepower of air compressors were needed just to hold the compressed air header pressure at 100 psi with no demand on the system. In most cases, these are spring brakes, so called because when no pressure is supplied, the brakes are applied by means of a spring. Proper air compressor maintenance can cut energy costs by approximately 1% and help prevent breakdowns that result in downtime and lost production (2). The other end of the brake adjuster is connected to a shaft that runs perpendicular to the plane formed by the pushrod and slack adjuster. After a stop, when the driver lifts his foot from the brake pedal, a quick release valve (14) allows brake actuation air to be quickly exhausted near the brakes it serves, rather than having to travel back through the supply line, thus speeding brake release time. Oil used to lubricate the air compressor may also mix with the air that passes through the compressor and settle at the bottom of the tank. Try to eliminate these completely, but if you must use them, consider using engineered nozzles for blow-offs. Compressed air is a very expensive resource, and one of the best ways to save energy is to operate the air compressor at the lowest possible discharge pressure. Establish a program to deal with alerts and analyze data to help you benefit from the information without getting overwhelmed. We have clearly established that compressed air systems are inefficient, expensive, and often misused. The ABS ejector ports can freeze up from lack of use. The shaft extends inboard and away from the wheel and is connected to a brake diaphragm chamber via an arm called a slack adjuster. Effect of brake chamber type (diaphragm area) on pushrod output force, with constant 60-psi application. Make sure you are looking at both the supply side and demand side. Why You Should & How To Drain Or Bleed RV Air Tanks - The Camping Nerd Figure 1. Hilton Philadelphia City Avenue, Philadelphia, PA, Hilton Los Angeles/Universal City Hotel, Los Angeles, California, USA, Institute for Learning & Innovation (ILI), Disability & Outreach and Inclusion Community (DORIC), www1.eere.energy.gov/femp/pdfs/compair_webinar_05162011.pdf, www.thecompressedairblog.com/energy-savings-checklist-for-your-compressed-air-system, https://energy.gov/sites/prod/files/2014/05/f16/compressed_air2.pdf, https://energy.gov/eere/amo/downloads/compressed-air-system-control-strategies, https://energy.gov/eere/amo/downloads/improving-compressed-air-system-performance-sourcebook-industry-third-edition. Both the supply and demand sides of a compressed air system are important, and they should be considered together when making decisions about the compressed air system (such as choosing the compressor type and capacity, location, receiver tanks, piping size and arrangement, etc.). Demand side: Piping distribution system. Air compressors compress air by forcing it into a smaller space. Dual-circuit air system - SGI - SGI Note: There is a circuit diagram of the air-supply subsystem here. (Keep in mind that the spring brakes will have already been applied once the air pressure drops to 60 psi.). During normal driving, air pressure is applied to the drive axle to stop the vehicle. A heated ejector valve is connected to the air compressors governor. In primary-secondary systems, chilled water flows through the chiller primary loop at a constant flow rate, whereas in the secondary loop, flow rate is varied according to the load. Drivers should know the normal pressure range of the vehicle they operate and should report any abnormal condition. I have an 04 Mack cv713 the primary air system keeps building air well past 140 but the secondary only builds up to 130 and takes about 20 minutes to build that much I've replaced the governor . 95 - 115 psi (6.6 - 7.9 bar) c. 110 - 120 psi (7.6 - 8.3 bar) d. 100 - 105 psi (7 - 7.2 bar) d ILI provides students and professionals lifelong learning opportunities to innovate through collaboration, practice, and career discovery. Ambient air is compressed and sent to storage tanks to be used by the brake system. Also, check out the U.S. Dept. Different manufacturing processes require different levels of air treatment. Estimate the compressed air load profile, i.e., how the demand in cubic feet per minute (CFM) changes over time. Zero-loss condensate drains operate similarly, but do not release any air during each drain cycle they only release the collected moisture and are therefore much more economical. The supply system Air treatment includes filtration and drying. Antilock braking systems (ABS) release the brakes when wheels lock up during a hard stop. However, it is one of the most inefficient, expensive, and misused utilities in manufacturing plants. A drop in air pressure below the normal cut-in setting is a sign that the air brake system is malfunctioning or that an abnormal demand is being placed on the system. On the secondary system, quick-release valves discharge air pressure from the front axle brake chambers to disengage the brakes. Figure 2 breaks down the energy consumption for a 100-kW energy input (1). Located on the vehicles instrument panel, the air pressure gauges let you know how much air pressure is in the air brake system to ensure the system is operating normally. Again, the better you maintain your total compressed air system, the more efficient and cost effective it will be. Moisture in the brake system can freeze in cold temperatures and may cause brake failure. Some rotors, such as Spartan Chassis cryogenically treated rotors, can handle even extreme temperatures. The effectiveness of the condensate removal system should also be evaluated. Table 1 lists some other possible misuses of compressed air and suggests alternatives (3). (kPa). Labelling of air pressure gauges varies, and some vehicles have additional air pressure gauges for other systems. As air pressure is exerted on the diaphragm, the pushrod on the other side of the diaphragm is extended. By checking this box and clicking the "Send me job offers" button below, I represent that I: By checking this box and clicking the "Send me job offers" button below. Spartan sets the foot control valve to apply 3 to 5 psi of air to the primary side before applying the secondary side. Under normal conditions, this valve does not need to operate. The brake adjusters length and the brake chambers size are two variables commonly altered to meet braking requirements. The split system ensures that, in the event of a failure, the entire system will not become inoperative, and the truck can be brought to a controlled stop. 1 Year Only about 510% of the energy input to a compressor goes toward productive use of compressed air. This compressed air is a form of stored energy. The product of these two values is expressed as the AL factor. This factor, when multiplied by 60 psi air pressure, is the industry standard for braking calculations. I have already replaced the two-way check valve. Instead of hydraulic wheel cylinders that expand the shoes, air brakes employ a shaft with cams on the end. An air dryer is not required by law, but most air-brake-equipped vehicles built today have one. In the event of over-pressurization, the safety valve allows air to escape, preventing damage to air lines, reservoirs and other components. Therefore, its recommended that the hydraulic brake fluid be replaced every two to three years. a. For example, if you are purchasing an air compressor for the supply side, you should consider the end-use loads, filters, and delivery piping on the demand side. Evaluate the compressor installations location, connection to cooling water, and ventilation. In CDL School Now The brake shoes expand when the shaft is twisted, and the cams act upon the rollers on the end of the brake shoes. The . As the shaft rotates, so does the cam. Table 1. Make sure all bearings are greased properly. The disc pads constantly ride on the rotor so they maintain an effective braking temperature. Why do air leaks tend to get ignored? Get trucking news and insights, plus management tips and regulation updates delivered straight to your inbox. If the mixture of moisture and oil that collects in the supply tank passes into the rest of the air brake system, it can damage brake components and interfere with the operation of the system. Spring brakes use spring tension to apply the parking brake; an air chamber releases the parking brake. The air that powers the brakes is delivered by an engine-driven air compressor. It wouldnt take long before the pushrod would not be able to extend far enough to apply the brakes. A detailed total system review revealed that even though more air compressors had been added, the piping delivery system had never been upgraded. In the event of a loss of system pressure, hold-off air pressure is overcome by the parking brake spring, and the brakes are automatically applied to provide emergency stopping. Verify that the sequencing and operation of the air compressors matches the operational compressed air demand profile. In round numbers, this 100-hp air compressor would cost approximately $40,000/yr just for the electricity. This establishes the point of "no pressure change" in the system because of the compressible nature of the air cushion within the tank. The air/oil separator, which is typically located at the exit of the air compressor, should be cleaned periodically. Fortunately, alternatives are available. Compressed air leaving the vehicle travels at a very high speed and will carry moisture, oil, dirt and dust. Important: A safety valve that is venting air means there is too much pressure building in the system, requiring immediate repair. And if cold drum brakes get wet, stopping power is reduced until the drum heats up and dries out. This publication has many good articles on ongoing compressed air system improvements. Also, pedal effort is minimal, because it simply involves depressing a treadle valve that sends air to the brake relay valves. This is accomplished with an anti-compounding valve, which is a quick-release valve with a double-check valve built into it. Read on to gain a better understanding of air brake systems. And, because the disc rotor is in the open air, repetitive use doesnt cause it to overheat like an enclosed drum. Drains should be located at low points in the header. Relay valves come in a variety of crack pressures. Important: A low air-pressure warning means there is a serious air brake system safety hazard. Convert air pressure into a strong mechanical force to apply the foundation brakes. Once air leaves the compressor and passes through the dryer, it arrives at the wet tank. Get it into a shop before your on the side of the road without any air. In addition to the inefficiencies inherent in the physics and thermodynamics of air compression, there are many other system inefficiencies, which are explored later in this article. To have a better experience, you need to: Tab to close the table of contents and return to the book. As air passes through, the material captures moisture and blow-by from the compressor. the blow-off is in operation on all shifts, all year. Estimate possible performance gains that could be achieved by operating the system in a different mode or using an alternative control strategy (3). As well, there is one located at the trailer air tank. Now that we know the purpose of secondary means of venting, let us discuss the equipment that can act as secondary means of venting. At this point, the dual circuits start. The first system is called the primary system. When the vehicle is parked, the dash valves are pulled out. If youre in a panic stop or begin to slide in slippery conditions, keep your foot on the brake pedal and allow the ABS to modulate the brake pressure. The foundation brakes A 4-inch long brake adjuster converts 1,000 pounds of force at the pushrod to 4,000 ib-in torque at the camshaft. Make sure that compressed air system optimization projects get into the capital budget cycle and do your homework to show the costs and benefits of an optimized compressed air system. These can be manually or automatically operated. From the wet tank, air then goes to the primary and secondary tanks. Two-way check valves are also used to allow dominant pressure to activate the stop light switch (12), and to release the parking brakes. In comparison, to calculate the cost of a low-pressure blower for a blow-off, assume: The electrical energy cost for the blow-off with compressed air is just over 4.5 times higher than that of using a low-pressure blower. All coolers and heat exchangers on the supply side should be cleaned periodically. Plants typically have hoses with nozzles for various functions. Primary tank goes to 125psi and the air governor purges. These compressed air cleanups, called blow-offs, typically include a pipe or a hose supplied with compressed air that feeds to one or more outlets or nozzles. A plant with 1,000 horsepower of air compressors operating at the same conditions would spend around $400,000/yr. The primary pump inlet would require 88 PSIG for the pressure relief valve to start to weep. As a result, the appropriate amount of park brake pressure is released in relation to the service brake pressure, preventing excessive torque from damaging the spring brakes. Watch the primary and secondary air pressure gauges (or needles, if the system has 2 needles in one gauge). And, 1,500 pounds multiplied by the 6-inch slack arm equals 9,000 inch-pounds of additional force. Have a 2015 kw t680 won't build secondary air pressure ,aired tank up holds thinking dryer possible am i going the right direction. Thats why diesel-powered Type A motorhomes usually are equipped with air brakes. Motor and air-end bearings. Fail 2 Years Leaks are common at many locations in a plant, such as: There are several approaches you can take to remedy air leaks. Understanding Air Brakes - Family RVing Magazine They contain compressed air with bleeder valve (screw type) with exit nozzle towards left side. ABS is rarely used. Disc brakes also arent affected by water as much as drum brakes. Job Listing Rules. It has a electron. Vehicles using air dryers must still have the air tanks drained regularly. Information on the demand load profile is very valuable for setting up the air compressor control system and determining the feasibility of using a VFD. Numerical Modelling of Cryogenic Tank Chilldown Using Charge-hold-vent Foundation brake operation. An understanding of how the components on the supply and demand sides interact is essential to the design and operation of an efficient compressed air system. The relay valves are similar to the quick-release valves but are connected directly to a reservoir for faster response and better airflow control. Its like an insurance policy invaluable if the need arises. 2023 - Family Rving Magazine All Rights Reserved. Although not mandated by law, an anti-compounding system can prevent such damage. The primary tank operates the rear brakes; the secondary tank operates the front brakes. Watch the primary and secondary air pressure gauges (or needles, if the system has two needles in one gauge). Conduct compressed air awareness training. The valves may have a heater to prevent freezing in cold weather. To avoid being in the direct path of air exhausting from the air brake system, you should be familiar with all the places where the compressed air exhausts. Disc brakes have better stopping power. The normal pressure range of an air brake system is determined by the cut-in and cut-out pressures. Oral fluid sampling added as a drug screening alternative to urinalysis and blood analysis. The main compressed air headers should be slightly sloped, with a pitch of about one inch per ten feet of pipe to allow water and condensate to drain out. Rich. the motor has a conversion factor of 0.746 kW/hp, the fan runs during half of the year, 4,380 hr/yr, five 1/8-in. Check the air gauges again. When the vehicle is in use, the dash-mounted parking brake valves are in the run (pushed-in) position. The spring brake automatically deploys when the pressure drops below 60 psi. The amount of friction produced is determined, in part, by the size of the brakes, the coefficient of friction (aggressiveness) of the brake lining material, and the mass and heat-rejection potential of the drum. To prevent the compressor from producing too much compressed air and to reduce the load on the engine, a governor is used in the air brake system. An alcohol evaporator adds an alcohol vapor to the air that will mix with any moisture or ice present and reduce its tendency to freeze. . Drum brakes function best at an operating temperature of about 475 degrees. Got that worked out? The shaft, in turn, is connected to an S-shaped cam between the brake shoes. Manual drain valves usually are operated by pulling lanyard cables in one of the wheel wells, but some motorhomes may have remote petcocks in a basement compartment, so be sure to check the owners manual for the location.On my Spartan chassis, each lanyard is color-coded so that I know which tank I am draining. I have separate gauges for each and they do not always have the same pressure in each. One, two, three or more tanks may be used, depending on the specific needs of the vehicle. A primer on system components and how they operate. When the brake pedal is released, air is restored to the spring brake chamber to release the brakes. These are required to be checked as part of the driver's pre-trip inspection. A 1/8-in.-dia. The plant had tried to remedy this problem by adding additional air compressors. Air Brakes Warning System - Pressure Guage Erratic Reading Always both tanks loose pressure. Smart valve positioners offer a range of diagnostics, but the volume of information they can provide can be daunting. In cases where there may appear to be only two air tanks, the primary tank is divided into two separate compartments with primary and wet chambers. On a motorhome with drum brakes, the air brakes are equipped with brake shoes and drums similar to a hydraulic brake system, but the mechanism to operate them is vastly different. In one case, a worker in a hot area took a compressed air source and directed the output onto himself to keep cool (Figure 3). Most air compressors use either centrifugal impellers (left) or rotary screws (right) to compress air. An ideal situation is to have one air compressor (or several) fully loaded and one additional air compressor with a variable-frequency drive (VFD) to handle the variable load on the demand side. More on that a little later. SOLVED: Our 2009 Kenworth T800, the low air pressure - Fixya And, many applications can be done more effectively or more efficiently using a method other than compressed air (2). Pressurized air moves from the supply reservoir to the primary reservoir (green) and the secondary reservoir (red) through one-way check valves. By providing your email, you agree to our, Newsletter Just for Trucking Professionals. Consider the overall layout of the distribution system piping. Blow-offs are frequently used to remove moisture or debris from parts during the manufacturing process (Figure 4). Cooling water quality. The valves momentarily expel moisture when the internal pressure differential is between 15 and 18 psi. the personal cooling is used during half of the year, in the hot months. Author: Rick. It is the operators who use the air on a daily basis. Most manufacturing plants provide annual training on various topics, particularly safety and hazardous materials. Computer hung up on my end across desktops so I patched it straight in. The compressed air piping that is being fed to the end user should come out of the top of the header to further eliminate entrained moisture in the air. Air pressure is usually measured in kiloPascals (kPa) or pounds per square inch (psi). Thus, the electrical costs of using compressed air can be significantly more than those of an alternative method, as the following two examples illustrate. There are many ways to contact the Government of Ontario. The pushrod is connected to one end of a lever called a brake adjuster often called a slack adjuster (20). By checking this box and clicking the "Send me job offers" button below, I represent that I: By checking this box and clicking the "Send me job offers" button below. Before driving a vehicle with a dual air system: xAllow time for the air compressor to build up a minimum of 100 psi pressure in both the primary and secondary systems. If moisture or condensation exists, it should condense and settle in this tank, which also serves as a buffer to remove any pulsing in the air as it passes down the line. air leak or equivalent air misuse costs about $1,000/yr in electricity. These brake chambers, (spring brakes), incorporate a second chamber, containing a second diaphragm and a powerful spring. One plant had an operation that required 125-psi compressed air supply pressure in order to operate properly. They operate by expanding a pair of shoes inside a spinning brake drum. This small change would save an estimated 12.5% in air compressor energy costs per year. But, chances are the motorhome will have them anyway, even if there is a wet tank. All components used to attach and power the air compressor must be kept in good condition to ensure a constant supply of compressed air. Most of these contaminants rest in the base of the unit. Involve everyone in the plant in reducing compressed air demand, including the accounting, purchasing, and product design departments, as well as manufacturing engineers, operators, maintenance technicians, and facilities technicians. Before driving a vehicle with a dual air system, allow time for the air compressor to build up a minimum of 100 psi pressure in both the primary and secondary systems. Both the primary and secondary tanks have pressure gauges located in the instrument panel, as well as a low-pressure alarm that will alert the driver any time the pressure in a system drops below 60 psi. Privacy | Consider the volume and locations of tanks for compressed air storage. Drivers should know the normal pressure range of the vehicle they operate and should report any abnormal condition. The plastic bowls on the bottom of filter/regulator/lubricators (FRLs) are notorious for leaks. A systems approach entails looking at the entire compressed air system, from start to finish, when considering optimization. The B400 tank will now allow the pressure in the tank to rise to 88 PSIG if the temperature jumps to 195F. It is essentially a lever, and a lever multiplies force in proportion to its length. Without your consent employers will not be able to contact with job offers, would you like to opt-in now? If energy costs $0.075/kW on average, what is the annual cost of running this compressor? Many plants use compressed air inappropriately. magazine. Inspecting Air Brake Systems | High Road Online CDL Training It looks like one large air tank, but it has a partition in the middle, and a check valve that screws in the side of the tank right near the middle. Section 5: Air Brakes - California DMV The primary air system operates the service brakes on the rear axle; the secondary air system operates the service brakes on the front axle. One recommendation was to buy a small standalone air compressor specifically for the machine that required the 125-psi air and reduce the pressure of the plant-wide compressed air system to 100 psi.