A second major way to classify commercial vehicles is by the job (vocation) the vehicle performs. Common vocational applications include:
■ Pick-up and delivery
■ Construction
■ Fire service
■ Heavy haul
■ Intercity coach
■ Line hal
■ Logging
■ Mining
■ Refuse collection
■ Rescue vehicles
■ School bus
■ Urban transit coach
The following sections discuss these classifications in greater detail
Pick-Up and Delivery
Vehicles classified primarily for picking-up and delivering goods and services operate mostly within cities and/or suburban areas. A delivery vehicle typically travels three miles (4.8 km) between starts/stops with a 100% load capacity going and 40% load on return. Common vehicles included in this category are:
■ Drop-bed auto haulers, as shown in FIGURE 1
■ Moving vans
■ Refrigerated delivery trucks
■ Beverage trucks
■ Municipal work trucks
■ Flatbed trucks
■ Parcel delivery trucks
■ Tow trucks and wreckers
A common configuration of vehicle in North America for pick-up and delivery operations is the straight or conventional truck configuration, such as the one shown in FIGURE 2. A straight truck used in the city typically has a single axle because weight limits on city streets are much lower than those on major highways. In addition, a single axle helps the vehicle to be more maneuverable. A cab-over-engine (COE) design, which places the cab over the front axle and engine, is exclusively used in Europe where shorter vehicle length regulations prevail and roads are often narrow and twisty with sharp turns. While less comfortable to operate, COE designs provide exceptional maneuverability because the vehicle is shorter and visibility is improved (FIGURE 3).
These vehicles use mid-bore diesel engines ranging from 3 to 7 L in displacement because of their superior fuel economy and superior low speed torque. This category of vehicle is the most adaptable vehicle for hybrid electric or battery electric operation since they do not travel far and return to a yard every day.
Construction
Vehicles used in construction are primarily engaged in moving material to and from a job site. Operating conditions are gen- erally 90% of loaded operation on road surfaces made of con- crete, asphalt, gravel, crushed rock, or hard-packed dirt, and up to 10% of loaded operation in loose sand or on muddy job sites. Maximum grades encountered are 12%. As a result, construc- tion vehicles tend to use short-step, deep-reduction transmis- sions combined with low-torque-rise engines providing more consistent torque over a wider engine speed range torque. Loads are distributed equally from side to side.
Common vehicles included in this category are:
■ Asphalt and gravel trucks, frequently referred to as dump trucks, as shown in FIGURE 4
■ Flatbed trucks hauling lumber and building supplies
■ Tank trucks, as shown in FIGURE 5
■ Landscape trucks, often referred to as tipper trucks out- side North America, as shown in FIGURE 6
■ Concrete mixers
■ Snowplows
Fire Service
These vehicles are used to transport people and equipment to extinguish fires, paramedics, or for ambulance services. Annual distances traveled are typically less than 20,000 miles (32,187 km) per year. Typical vehicle routes are three miles (4.8 km) between start and stop. High deceleration stops are frequent.
Common vehicles in this category are:
■ Aerial ladders and fire trucks, as shown in FIGURE 7
■ Pumpers tankers
■ Aerial platforms and special applications, as shown in FIGURE 8 FIGURE 9
■ Ambulance/paramedic
Heavy Haul
Vehicles in the heavy-haul category move heavy equipment or materials at legal maximums for length, width, and weight. They may exceed those limits with special loading permits. Operation is mostly on road surfaces made of concrete, asphalt, and maintained gravel. Load weights are 100% of vehicle capacity going and empty on return. Vehicles in this classification require high horsepower, high-torque-rise engines with the ability to pull the heaviest loads. FIGURE 9 illustrates a typical heavy- haul configuration.
Typical vehicle types in this category are:
■ Equipment-hauling flatbed trailers
■ Steel haulers using high or low trailers
Intercity Coach
This category of vehicle transports people, and occasionally light freight, between cities and/or suburban areas. Intercity coaches travel on highway and in urban conditions accumulating high mileage on routes exceeding 30 miles (48.3 km) between start and stop.
Typical vehicle types in this category are:
■ Tour coaches
■ Cross-country coaches
Line Haul
Line-haul trucks move freight over long distances-generally over 60,000 miles/year (96,561 km/year). More than 30 miles (48.3 km) of distance between starting and stopping are typical for line-haul service. Straight trucks (trucks with only a box) use either single or tandem axles. Tractor-trailer combinations are most common.
Typical line-haul vehicles include:
■ General freight trucks in either straight or tractor-trailer configurations, such as shown in FIGURE 10
Refrigerated food trucks
■ Livestock tractor trailers
■ Flatbed trailers, such as the one in FIGURE 11
■ Side curtains, as shown in FIGURE 12, that enable fast pallet unloading and loading with forklift trucks
Line-haul trucks travel long distances with heavy loads and at high speeds. As a result, line-haul trucks have unique vehicle requirements for their engines, tires, suspensions, cab configu rations, etc.
Logging
Logging trucks move shipments of wood logs, chips, and pulp between logging sites or to and from logging or paper mills. Logging trucks travel distances of 3 to 30 miles (4.8 to 48.3 km) between starts and stops. Mostly, they travel on road surfaces of concrete, asphalt, maintained gravel, crushed rock, or hard- packed dirt, but up to 10% of their loaded operation can occur on sandy or muddy job sites. Trucks are loaded to 100% capacity when delivering loads and empty when returning.
Typical logging vehicles are:
■ Wood-chip haulers-either a straight truck or tractor and trailer
■ Log-hauling tractor-trailer combinations, as shown in FIGURE 13
Logging trucks that operate in off-road conditions have unique requirements for specialized traction capabilities pro- vided by tires and drive axles. Heavy frames are also needed to resist damage from twisting and bending. Suspensions are designed to better handle severe off-road terrains while carry- ing the heaviest possible loads.
Mining
Mining operation trucks move rock, ore, gravel, and other min- erals. Average trip distances are 30 miles (48.3 km) between starting and stopping. While most operations are on-highway, up to 10% of distances traveled are over sandy or muddy job sites. The trucks are typically 100% loaded while delivering and empty on return trips.
Typical mining vehicle types are:
■ Belly dump trailers
■ Semi-end dump hopper trailer combinations
The gravel hauler in FIGURE 14 is an example of a mining application. The tilting dump box requires a power take-off to operate a hydraulic pump called a wet-line.
Refuse Collection
Refuse vehicles, better known as garbage trucks, are used for pick-up and transportation of residential garbage or recycling materials. These vehicles encounter steep grades of up to 20% when they travel into landfill, transfer, or recycling sites. Refuse trucks typically have a high proportion of starts and stops for every mile traveled.
Typical refuse vehicles are:
■ Front-/rear-/side-loading garbage trucks, as shown in FIGURE 15
■ Sewer/septic/vacuum trucks
■ Liquid waste haulers
To enable the greatest level of maneuverability and highest load capacity, refuse vehicles are typically built on low-entry, COE chassis.
Rescue Vehicles
Rescue vehicles are specialized vehicles designed for rapid acceleration to crash sites on highways or airport tarmacs away from hydrant hookups. They are low mileage opera- tion vehicles with high horsepower engines and automatic transmissions.
Typical rescue vehicle types are:
■ Airport Rescue Fire (ARF) Crash Rescue Fire (CRF)
■ Rapid Intervention Vehicle (RIV) Emergency Service
Some of the most powerful trucks with the fastest acceleration rates are crash-and-rescue trucks, as shown in FIGURE 16. These trucks are used to quickly extinguish fires at airports or on the highway because of accidents. As a result, crash-and- rescue trucks require high-speed capabilities while carrying heavy loads.
School Bus
School buses are familiar people haulers that transport students to and from school or school-related events. Two stops per mile over mixed road surfaces are typical. School buses frequently operate under fully loaded capacity.
Typical school bus configurations are:
■ Front-engine commercial chassis
■ Front-or rear-engine integral coach, as shown in FIGURE 17
Urban Transit Coach
As the name indicates, urban transit coaches are the city buses that transport people in and around cities or suburban areas. City buses operate on well-maintained highways and residential streets made of asphalt or concrete. These units have a high frequency of starts and stops per mile-nine is considered typical.
Typical urban transit vehicles are:
■ Airport shuttle buses
■ City transit buses, such as the one in FIGURE 18
These can come in a range of configurations, as shown in FIGURE 19A and FIGURE 19B, including double deckers and articulated or "bendy buses," as they are known in some countries.
