Chapter 1 Introduction to Heavy-Duty Commercial Vehicles

Size: px

Start display at page:

Download "Chapter 1 Introduction to Heavy-Duty Commercial Vehicles"

Sydney Mitchell
5 years ago
Views:

1 Chapter 1 Introduction to Heavy-Duty Commercial Vehicles

2 Introduction Categories and configurations of commercial vehicles include: Medium-sized delivery vehicles Ambulances Fire and rescue vehicles Highway semi-trailers Gravel haulers Fuel tankers Utility trucks Highway coaches Urban transit buses

3 Introduction In this chapter we will show you: A range of commercial vehicles Their applications The set of fundamental skills required for working on them Their specialized requirements

4 Classification of Application by Operational Characteristics To classify commercial vehicles: Consider where a commercial vehicle performs its primary job Operating conditions Turnpike or interstate On-highway On-/off-highway or mountainous highway Off-highway Urban

5 Classification of Application by Operational Characteristics Turnpike or Interstate Factors: road materials, vehicle speeds, amount of stop-and-go driving, degree of road crown Vehicles designed to run on limited-access, well-maintained, multi-lane highways made of excellent concrete or asphalt with maximum adverse grades not in excess of 3%

6 Classification of Application by Operational Characteristics On-Highway Operate on well-maintained major highways of excellent concrete or asphalt construction Roads level to rolling with maximum grades to 8% Vehicles must operate within legal weight and dimensional limitations Vehicles able to handle steeper grades

7 Classification of Application by Operational Characteristics On-/Off-Highway or Mountainous Highway 20% total operating time on secondary roads Roads made from good concrete or asphalt with intermittent grades of up to 12% Remaining time travelled on road of well-maintained crushed rock or similar material Subject to legal weight and dimensional limitations

8 Classification of Application by Operational Characteristics Off-Highway 20% travel time on gravel roads or roads with maintained crushed rock surface Maximum grade 12% Grades of 8% frequently encountered Not generally subject to legal weight or dimensional limitations

9 Classification of Application by Urban Operational Characteristics Operating conditions primarily within cities and suburban areas Subject to frequent stops and starts Roads of concrete, asphalt, maintained gravel surfaces Greater levels of maneuverability than other classes Often use engines with a lower power output

10 Vocational Applications of Commercial Vehicles Pick-up and delivery Construction Fire service Heavy haul Intercity coach Line haul Logging Mining Refuse collection Rescue vehicles School bus Urban transit coach

11 Vocational Applications of Commercial Vehicles Pick-up and Delivery Drop bed auto haulers Moving vans Refrigerated delivery trucks Beverage trucks Municipal trucks Flatbed trucks Newspaper delivery trucks Tow trucks and wreckers

12 Vocational Applications of Commercial Vehicles Construction Asphalt and gravel trucks (dump truck) Flatbed trucks Tank trucks Landscape trucks (tipper truck) Concrete mixers Snowplows

13 Fire Service Vocational Applications of Commercial Vehicles Aerial ladders and fire trucks Pumpers tankers Aerial platforms and special applications Ambulance/ paramedic

14 Vocational Applications of Commercial Vehicles Heavy Haul Equipment hauling flatbed trailers Steel haulers using high or low trailers

15 Vocational Applications of Commercial Vehicles Intercity Coach Transports people and light freight between cities and/or suburban areas Tour coaches Cross country coaches

16 Vocational Applications of Commercial Vehicles Line-Haul General freight trucks in straight or tractor trailer configurations Refrigerated food trucks Livestock tractor trailers Flatbed trailers Side curtains

17 Logging Vocational Applications of Commercial Vehicles Wood chip haulers either straight truck or tractor and trailer Log hauling tractor trailer combinations

18 Vocational Applications of Commercial Vehicles Mining Belly dump trailers Semi-end dump hopper trailer combinations Gravel hauler

19 Vocational Applications of Commercial Vehicles Refuse Collection Front-/rear-/sideloading garbage trucks Sewer/septic/vacuu m trucks Liquid waste haulers

20 Vocational Applications of Commercial Vehicles Rescue Vehicles Airport Rescue Fire (ARF) Crash Rescue Fire (CRF) Rapid Intervention Vehicle (RIV) Emergency Service

21 School Bus Vocational Applications of Commercial Vehicles Front-engine commercial chassis Front- or rearengine integral coach

22 Vocational Applications of Commercial Vehicles Urban Transit Coach Airport shuttle buses City transit buses

23 Design Factors for Vocational Applications Chassis Frame Frame rails of a truck or bus are vehicle s backbone All equipment must mount or attach to frame Frame must be sized and built appropriately

24 Engines Design Factors for Vocational Applications Must have sufficient power to move heavy loads and accelerate up grades while providing good fuel economy Torque: twisting force applied to crankshaft Horsepower: how fast engine can turn while producing torque

25 Engines Design Factors for Vocational Applications Torque rise: difference between engine torque produced at rated speed and peak torque High-torque-rise engines: used for line haul applications; have a steep increase in torque Low-torque-rise engines: produce torque over a wider engine RPM operating range

26 Power Trains Design Factors for Vocational Applications Commercial vehicles require power trains designed specifically for particular vocations Startability: capability to commence moving forward on a specified grade Gradability: capability to maintain forward motion on specified grade while sustaining a minimum speed

27 Design Factors for Vocational Applications

28 Design Factors for Vocational Applications Power Trains Tractors and trucks classified according to their drive and non-drive axle configurations Factors influencing rear axle selection: Gross combination vehicle weight (GCVW) Type of terrain Road speed Tire size Axle ratio required and transmission ratios Engine torque and speed

29 Power Trains Design Factors for Vocational Applications Trucks categorized by number of wheel positions and drive axles Common configuration is tandem axle; uses two drive axles Pusher axle is non-driving and located in front of a drive axle Tag axle located behind the drive axles

30 Design Factors for Vocational Applications

31 Cab Design Factors for Vocational Applications Designed for specific types of usage Include some type of aerodynamic fairings and wind deflectors to improve fuel economy Conventional cab: engine placed in front of the cab Location of front axle can influence turning radius of a vehicle and affect ride quality

32 Design Factors for Vocational Applications

33 Suspensions Design Factors for Vocational Applications Transmits braking and drive forces to chassis Enables articulation or movement of axles to adapt to road conditions Promotes proper vehicle tracking while enabling safe steering and minimization of tire wear

34 Other Chassis Equipment Fuel tanks Exhaust Hitching devices and fifth wheels Batteries Auxiliary power supplies Auxiliary heaters Back of cab access Day cab or sleeper cab Seating Power take-off s Steps Lighting and conspicuity markings Deck plates Braking systems Auxiliary braking devices Aerodynamic fairings Tires

35 Classification of Heavy Vehicles by Weight and Length Federal Bridge Gross Weight Formula Gross weight limits: maximum legal weight of a vehicle that can travel on roads and bridges Federal Bridge Gross Weight Formula (Bridge Formula B and Federal Bridge Formula) Formulas established maximum weights for commercial motor vehicle (CMV) based on number of axles vehicle had and spacing between those axles

36 Classification of Heavy Vehicles by Weight and Length Vehicle Weight Ratings Gross vehicle weight (GVW): maximum design weight of a vehicle including full tank of fuel, fully loaded to its capacity, with all passengers Gross vehicle weight rating (GVWR): design rating specified by a manufacturer as recommended maximum weight of a vehicle when fully loaded

37 Classification of Heavy Vehicles by Weight and Length Vehicle Weight Ratings Gross combined weight rating (GCWR): specific maximum weight limit determined by vehicle manufacturer

38 Classification of Heavy Vehicles by Combination Combination vehicles Two or more combined or coupled vehicle units Full trailer Trailer supported at both ends with an axle and does not rest on fifth wheel Semi-trailer Coupling method where some of trailer s load is carried by tractor through connection known as a fifth wheel

39 Classification of Heavy Vehicles by Combination A-Train Second trailer is full trailer unit connected by draw bar to single hitch point on lead trailer B-Train Tractor pulling semi-trailer and a second, semi-trailer behind the first semi-trailer C-Trains Similar to A-train except that it has two drawbars and is more stable

40 Classification of Heavy Vehicles by Combination

41 Classification of Heavy Vehicles by Combination Hitching Devices Fifth wheels: plate-type coupling device designed to support weight of semi-trailer Draw bars: connect tow vehicles to tractor or lead towing unit Pintle hooks: fixed towing horn that connects with drawbar eye attached to towed vehicle Couplers: look similar to pintle hooks; towing horn pivots and is not fixed Ball hitches: used with tongue-trailer draw bars

42 Common Terms and Conventions Vehicle Identification Number (VIN) Unique serial number composed of 17 characters (letters and digits) assigned to each vehicle produced Located on frame, engine, inside driver's door on information sticker, on some components and in vehicle's computer modules.

43 Summary Commercial vehicles perform variety of revenue-generating tasks having unique and even unusual functions. To properly maintain and service commercial vehicles, important to understand the ways commercial vehicles are classified and configured. Helpful way to classify commercial vehicles is considering where it performs its primary job.

44 Summary When classifying commercial vehicles by operating conditions, five categories used: Turnpike or interstate; on-highway; on-/offhighway or mountainous highway; off-highway; and urban. Vehicles classified by their vocation. Depending on operating conditions and job performed, commercial vehicle will have a particular chassis, engine, power train, cab, and suspension.

45 Summary Frames sized and built appropriately to be capable of supporting loads applied to it while adapting to forces that bend and twist frame. Heavy-vehicle engines must have sufficient power to move heavy loads and accelerate up grades while providing good fuel economy. Commercial vehicles require power trains designed specifically for particular vocations. Tractors and trucks classified according to their drive and non-drive axle configurations.

46 Summary Common configuration is tandem axle combination, which uses use two drive axles. Commercial vehicles classified by weight and length. Federal Bridge Gross Weight Formula: legal calculation that establishes maximum allowable weight of commercial vehicle traveling on roads and bridges. Classification system for heavy vehicles uses their gross vehicle weight (GVW).

47 Summary In North America, vehicle s weight per axle is regulated. Heavy vehicles classified by combination: tractor/semi-trailer, truck/full trailer, truck/pole trailer. Combinations have multiple trailers, referred to as A-trains, B-trains, C-trains; differentiated by hitching mechanism connecting the trailers.

48 Summary Best solution to enable transportation of heavier and larger loads is to add more axles to vehicle configuration. Fifth wheel is point of articulation between trailer and tractor and enables trailer and tractor to turn effectively. Vehicle classifications by hitching device rely on gross trailer rate and tongue weight.

Application Guidelines DAAG-0080 February 2018

Spicer Drive Axles Application Guidelines DAAG-0080 February 2018 Table of Contents Introduction Important Information about These Guidelines...1 Purpose...1 Use of Guidelines...1 Drive Warranties...1