1 An engine from the West Whiteland Fire Company in Exton, Pennsylvania, approaches the skid test
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Posted: Aug 3, 2017
By Chris Daly
To bring a fire apparatus to a stop, the driver must perceive a hazard in the road, react to the hazard in the road, and decelerate the vehicle to a stop.
The distance it takes the driver to decelerate to a stop is commonly called the “skid-to-stop distance.” To determine the skid-to-stop distance, an investigator must know three things: the coefficient of friction of the road (how “sticky” the road is), the slope of the road, and the braking efficiency of the vehicle.
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| This illustrates the difference in stopping distance between a passenger vehicle and a fire apparatus that are both skidding to a stop on a dry road. Note how much further the fire apparatus will skid. If the fire apparatus operator does not account for this added skid distance, he may find himself involved in a serious crash. |
A vehicle’s braking efficiency plays a major role in determining skid distance. Braking efficiency is the amount of available roadway friction the vehicle can use as it skids to a stop. While most passenger vehicles are equipped with a hydraulic braking system that provides near 100 percent braking efficiency, commercial vehicles do not share this luxury. This is because of the rubber composition of a truck tire and the lag time of the air brake system.
Truck Tires
Truck tires are designed to carry heavy loads over long distances without wearing out. Truck tires are made out of a more durable rubber that makes them more resistant to tire wear. The downside to this more durable rubber is that it does not grip the road as well as a car tire. As a result, a truck tire will travel a farther distance if it skids on the road. While a car ti re will provide a smoother ride and grip the road better, the soft rubber tends to wear out more quickly.
Mechanical Lag Time
When a driver presses his foot on the brake pedal, there will be a time delay before the brakes fully engage. In a hydraulically braked vehicle, such as a passenger car, this lag time is negligible. It does not take much time for the hydraulic braking system to pressurize and engage the brakes. On the other hand, a vehicle equipped with air brakes will have a much longer lag time after the driver presses his foot on the brake pedal. This is because it takes more time for the air pressure to build inside the system and fully engage the brakes. Depending on the age and the condition of the vehicle, this lag time may be upward of a half second. If the vehicle is traveling at highway speeds, it may take more than 100 feet before the air brakes fully engage.
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1 An engine from the West Whiteland Fire Company in Exton, Pennsylvania, approaches the skid test
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Posted: Aug 3, 2017
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Christian P. Koop |
In December 2012, I wrote an article titled “Battery Management for Emergency Vehicles” that was basically about charging systems and how important it is to keep batteries properly charged and maintained in emergency response vehicles (ERVs).
I also briefly talked about an alternative method to aid in charging a battery bank that is very efficient - solar panels. Solar panel technology has improved greatly and has become more affordable over the past few years. Its use in helping to keep battery banks fully charged is invaluable, particularly for ERVs that are relied on to start without fail for emergencies. I will delve more into solar panels in this article. But before I do, I will explain the different types of batteries available; how they differ; and, most importantly, how solar panels not only can help keep them properly charged but also can extend their lives and improve the bottom line of any organization that recognizes how important and beneficial they can be and puts them to use.
Battery Technology
Battery technology has evolved over the years. But before I mention the different automotive and heavy-duty types available today, I must give credit to the inventor of the storage battery. Allesandro Volta invented the first modern dry storage battery in 1796. The first batteries may have actually been used as far back as 250 BC. A French physicist, Gaston Plante, invented the first wet lead acid storage battery in 1860, which paved the way for the development of automotive charging systems because the dry-type storage batteries first used in the early automobiles could not be recharged. Battery technology has changed and improved significantly over the years. The lead acid storage battery has evolved into several types.
Today there are two types of lead acid (LA) batteries: starting (aka cranking) and deep cycle. Under these two LA battery types there are three subcategories: wet cell (flooded), gel cell, and absorbed glass matt (AGM). Of these three, the wet cell is available in serviceable and maintenance-free versions, or they are sealed and filled with electrolyte. Electrolyte is a mix of water and sulfuric acid that provides the path for the chemical reaction that takes place between the lead and lead dioxide plates in the battery to produce electricity.
The starting battery is the one most commonly used with ERVs and has more and thinner plates to provide high amperage very quickly for starting. The deep cycle has thicker plates to provide current over longer periods of time, although it cannot provide as much instant energy as the starting battery. Gel batteries have a nonliquid jelly type of electrolyte because silica has been added to the electrolyte. Because of this, they can be mounted in many positions. Gel batteries are designed for deep-cycle applications and typically need a reduced voltage to recharge. AGM batteries are considered dual-purpose or a cross between cranking and deep cycle. Although they have liquid electrolyte, it is suspended. Both the gel and AGM store well and do not sulfate as easily as the wet cell. Both cost much more than the wet cell and require different charge rates. Because of this, they may require specialty chargers. A cranking battery may only tolerate 10 heavy deep cycles before it kicks the bucket, while a deep cycle may be able to go 300 deep cycles.
Keeping Them Charged
In my past article, I compared batteries to a checking account. If you continuously withdraw money from your account without making timely deposits, you
Read more
- 178
- Article rating: No rating
Posted: Aug 3, 2017
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|
Christian P. Koop |
In December 2012, I wrote an article titled “Battery Management for Emergency Vehicles” that was basically about charging systems and how important it is to keep batteries properly charged and maintained in emergency response vehicles (ERVs).
I also briefly talked about an alternative method to aid in charging a battery bank that is very efficient - solar panels. Solar panel technology has improved greatly and has become more affordable over the past few years. Its use in helping to keep battery banks fully charged is invaluable, particularly for ERVs that are relied on to start without fail for emergencies. I will delve more into solar panels in this article. But before I do, I will explain the different types of batteries available; how they differ; and, most importantly, how solar panels not only can help keep them properly charged but also can extend their lives and improve the bottom line of any organization that recognizes how important and beneficial they can be and puts them to use.
Battery Technology
Battery technology has evolved over the years. But before I mention the different automotive and heavy-duty types available today, I must give credit to the inventor of the storage battery. Allesandro Volta invented the first modern dry storage battery in 1796. The first batteries may have actually been used as far back as 250 BC. A French physicist, Gaston Plante, invented the first wet lead acid storage battery in 1860, which paved the way for the development of automotive charging systems because the dry-type storage batteries first used in the early automobiles could not be recharged. Battery technology has changed and improved significantly over the years. The lead acid storage battery has evolved into several types.
Today there are two types of lead acid (LA) batteries: starting (aka cranking) and deep cycle. Under these two LA battery types there are three subcategories: wet cell (flooded), gel cell, and absorbed glass matt (AGM). Of these three, the wet cell is available in serviceable and maintenance-free versions, or they are sealed and filled with electrolyte. Electrolyte is a mix of water and sulfuric acid that provides the path for the chemical reaction that takes place between the lead and lead dioxide plates in the battery to produce electricity.
The starting battery is the one most commonly used with ERVs and has more and thinner plates to provide high amperage very quickly for starting. The deep cycle has thicker plates to provide current over longer periods of time, although it cannot provide as much instant energy as the starting battery. Gel batteries have a nonliquid jelly type of electrolyte because silica has been added to the electrolyte. Because of this, they can be mounted in many positions. Gel batteries are designed for deep-cycle applications and typically need a reduced voltage to recharge. AGM batteries are considered dual-purpose or a cross between cranking and deep cycle. Although they have liquid electrolyte, it is suspended. Both the gel and AGM store well and do not sulfate as easily as the wet cell. Both cost much more than the wet cell and require different charge rates. Because of this, they may require specialty chargers. A cranking battery may only tolerate 10 heavy deep cycles before it kicks the bucket, while a deep cycle may be able to go 300 deep cycles.
Keeping Them Charged
In my past article, I compared batteries to a checking account. If you continuously withdraw money from your account without making timely deposits, you
Read more
- 169
- Article rating: No rating
Posted: Aug 3, 2017
|
|
Christian P. Koop |
In December 2012, I wrote an article titled “Battery Management for Emergency Vehicles” that was basically about charging systems and how important it is to keep batteries properly charged and maintained in emergency response vehicles (ERVs).
I also briefly talked about an alternative method to aid in charging a battery bank that is very efficient - solar panels. Solar panel technology has improved greatly and has become more affordable over the past few years. Its use in helping to keep battery banks fully charged is invaluable, particularly for ERVs that are relied on to start without fail for emergencies. I will delve more into solar panels in this article. But before I do, I will explain the different types of batteries available; how they differ; and, most importantly, how solar panels not only can help keep them properly charged but also can extend their lives and improve the bottom line of any organization that recognizes how important and beneficial they can be and puts them to use.
Battery Technology
Battery technology has evolved over the years. But before I mention the different automotive and heavy-duty types available today, I must give credit to the inventor of the storage battery. Allesandro Volta invented the first modern dry storage battery in 1796. The first batteries may have actually been used as far back as 250 BC. A French physicist, Gaston Plante, invented the first wet lead acid storage battery in 1860, which paved the way for the development of automotive charging systems because the dry-type storage batteries first used in the early automobiles could not be recharged. Battery technology has changed and improved significantly over the years. The lead acid storage battery has evolved into several types.
Today there are two types of lead acid (LA) batteries: starting (aka cranking) and deep cycle. Under these two LA battery types there are three subcategories: wet cell (flooded), gel cell, and absorbed glass matt (AGM). Of these three, the wet cell is available in serviceable and maintenance-free versions, or they are sealed and filled with electrolyte. Electrolyte is a mix of water and sulfuric acid that provides the path for the chemical reaction that takes place between the lead and lead dioxide plates in the battery to produce electricity.
The starting battery is the one most commonly used with ERVs and has more and thinner plates to provide high amperage very quickly for starting. The deep cycle has thicker plates to provide current over longer periods of time, although it cannot provide as much instant energy as the starting battery. Gel batteries have a nonliquid jelly type of electrolyte because silica has been added to the electrolyte. Because of this, they can be mounted in many positions. Gel batteries are designed for deep-cycle applications and typically need a reduced voltage to recharge. AGM batteries are considered dual-purpose or a cross between cranking and deep cycle. Although they have liquid electrolyte, it is suspended. Both the gel and AGM store well and do not sulfate as easily as the wet cell. Both cost much more than the wet cell and require different charge rates. Because of this, they may require specialty chargers. A cranking battery may only tolerate 10 heavy deep cycles before it kicks the bucket, while a deep cycle may be able to go 300 deep cycles.
Keeping Them Charged
In my past article, I compared batteries to a checking account. If you continuously withdraw money from your account without making timely deposits, you
Read more
- 168
- Article rating: No rating
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