VEHICLE BODY ENGINEERING - UNIT 3 Commercial vehicle details

Notes for Subject vehicle body engineering

1. UNIT - 3 COMMERCIAL VEHICLE DETAILS

2. CONTENT 01 Types of Commercial Vehicle Body 02 Construction details on flat platform body 03 Dimensions of driver seats 04 Drivers cab design

3. Types of Commercial Vehicle Body Based On Load-carrying Platform Normal Flat Floor Lowered Floor with Wheel Arches Based on Usage & Industry Based on Refrigeration Type Based On Engine Mounting Front Engine Mounted Vehicles Mid Engine Mounted Vehicles Rear Engine Mounted Vehicles

4. Front Engine Mounted Vehicles Conventional Trucks & Buses – Engine is mounted at the front, allowing easy access for maintenance and better cooling. Examples: Heavy-duty trucks, long-haul transporters, most city buses. Cab-Over-Engine (COE) Vehicles – Engine is placed under the driver's cab, reducing overall length and improving maneuverability. Examples: Box trucks, delivery vans, municipal buses.

5. Mid Engine Mounted Vehicles Low-Floor Buses – Engine is placed in the middle (under the floor) to allow a flat passenger area . Examples: Urban transit buses, articulated buses. Specialty Vehicles – Some fire trucks or high-performance utility vehicles use mid-engine placement for better weight distribution.

6. Rear Engine Mounted Vehicles Luxury & City Buses – Engine is mounted at the rear, providing better comfort by reducing noise and heat in the passenger area. Examples: Intercity coaches, articulated buses. Garbage Trucks & Specialized Utility Vehicles – Rear - mounted engines provide better weight distribution for heavy loads.

7. (B) Lowered Floor with Wheel Arches – The floor is lowered between the wheel wells to increase interior height, but wheel arches protrude into the cargo space. Found in light commercial vans, minibuses, and low-floor city buses. Beneficial for easier loading, increased headroom, and better passenger access in buses. Based on Load-Carrying Platform (A) Normal Flat Floor – The cargo area has a completely level surface without interruptions. Common in flatbed trucks, box trucks, and standard cargo vans. Ideal for heavy-duty transport, palletized goods, and industrial materials.

8. (C) Based on Usage & Industry 1. Goods Carrier – Used for transporting various types of goods, including general cargo, refrigerated items, and bulk materials. Box Trucks/Vans – Enclosed cargo space for general goods and parcels. Flatbed Trucks – Open platform for heavy or irregularly shaped loads. Curtain-Sider Trucks – Flexible sliding curtains for easy side loading/unloading. Tanker Trucks – Cylindrical tanks for transporting liquids like fuel, milk, and chemicals.

9. (C) Based on Usage & Industry 2. Construction Vehicles – Heavy-duty vehicles used in construction, roadwork, and infrastructure projects. Dump Trucks (Tippers) – Hydraulic system for unloading materials like sand, gravel, or debris. Concrete Mixers – Rotating drum for mixing and transporting concrete . Bulldozers & Excavators – Earthmoving equipment (sometimes mounted on transport trucks).

10. Based on Insulation & Body Type Based on Cooling System Ice-Cooled Trucks – Use ice or dry ice for short-distance transport. Mechanical Refrigeration Trucks – Equipped with a compressor - driven refrigeration unit. Cryogenic Refrigeration Trucks – Use liquid nitrogen or CO₂ to maintain ultra-low temperatures. Fully Insulated Vans – Standard cargo vans with thermal insulation for temperature retention. Refrigerated Box Trucks – Rigid, temperature-controlled box mounted on a chassis. Refrigerated Semi-Trailers – Large trailers with advanced cooling systems for long-haul transport. (D) Based on Refrigeration Type

11. Structural Components of a Flat Platform Body Constructed from high-tensile steel, aluminum, or composite materials to support heavy loads. Reinforced with longitudinal beams and cross-members for additional structural strength. Mounted on the truck's main chassis using U-bolts or welded joints for stability. Chassis Frame Lashing Hooks & Tie-Down Points – Used to secure cargo with ropes, straps, or chains. Stake Pockets – Slots along the edges to insert removable side stakes for additional cargo support. Side Rails (Optional) – Low-profile rails along the edges to prevent cargo from shifting. Load Retention Features Mounted to the Truck’s Chassis – Either bolted or welded for a secure attachment. Leaf Spring or Air Suspension – Helps absorb road shocks and vibrations to protect cargo. Mounting & Suspension System Longitudinal Beams – Run along the length of the platform to distribute weight evenly. Cross-Members (Underframe Supports) – Installed at regular intervals to provide strength and prevent sagging. Mudguards & Fenders – Installed over the wheels to protect the cargo from dirt and debris. Support & Reinforcement Mild Steel (MS) Plates – Strong & durable, commonly used in heavy - duty applications. Aluminum – Lightweight & corrosion-resistant but less durable than steel. Wooden Planks (Hardwood/Plywood) – Used in some cases to provide shock absorption. Composite Materials – A combination of steel & aluminum for a balance of strength & weight. Flooring (Decking Material)

12. Applications of Flat Platform Bodies Construction Materials Transport (Steel bars, cement bags, bricks). Heavy Machinery & Equipment Hauling (Excavators, generators, industrial machines). Agricultural Use (Transporting logs, hay bales, and farm equipment). Container Transport (Can carry intermodal containers with twist locks).

13. TRAILER A trailer is a non-motorized vehicle designed to be towed by a truck or tractor unit. It is commonly used for transporting heavy loads, goods, and specialized cargo over long distances.

14. Types of Trailers Tanker Trailer Cylindrical tank body for transporting liquids, gases, or chemicals. Side Dump Trailer Hydraulic system enables side unloading of loose materials like sand, gravel, and coal. Flatbed Trailer Open platform with no sides or roof, ideal for construction materials, machinery, and oversized loads. Lowboy Trailer (Step-Deck Trailer) Lowered deck to accommodate tall and heavy machinery like excavators. 01 04 05 Curtain-Side Trailer Side panels made of flexible curtains for easy loading/unloading while providing weather protection. Box Trailer(Enclosed Trailer) Fully enclosed cargo area for general goods, electronics, and weather-sensitive cargo. 02 06 Car Carrier Trailer Multi-level platform for transporting multiple vehicles. Refrigerated Trailer (Reefer) Insulated and equipped with temperature control for perishable goods (e.g., food, pharmaceuticals). 03 07 08 09 10 Logging Trailer Designed for transporting logs with adjustable stakes to hold timber securely. Tipper Trailer (End Dump Trailer) Uses a hydraulic lift to tilt the cargo bed and unload at the rear.

15. Construction Details of a Trailer Chassis & Frame – Made from high-tensile steel or aluminum to provide strength and durability. I-Beam or Box-Frame Construction to support heavy loads. Cross-members reinforce the structure for weight distribution. Suspension System – Leaf Spring Suspension – Common in heavy-duty trailers for shock absorption. Air Suspension – Used for better load stability and smooth rides. Torsion Axle Suspension – Provides independent movement for improved road handling. Axles & Wheels – Single-Axle Trailer – Used for lighter loads and smaller trailers. Tandem-Axle Trailer – Two axles for better load distribution and stability. Multi-Axle Trailer – Used for heavy-duty applications like transporting construction equipment.

16. Construction Details of a Trailer Braking System – Electric Brakes – Controlled by the towing vehicle for smooth stopping. Air Brakes – Used in heavy trailers for effective braking performance. Hydraulic Brakes – Used in medium-sized trailers for controlled stopping. Coupling & Hitching System – Fifth Wheel Coupling – Used for semi-trailers, allowing flexibility and easy detachment. Gooseneck Hitch – A stronger hitching system mounted inside the towing vehicle’s bed. Pintle Hook – Used in military and off-road applications for high articulation.

17. Applications of Trailers Logistics & Freight Transport – Moving goods, food products, and consumer items. Construction Industry – Carrying raw materials, heavy equipment, and debris. Agriculture – Transporting grains, livestock, and farm produce. Oil & Gas Industry – Carrying fuel, LPG, and hazardous chemicals. Automotive Industry – Moving new or used cars and vehicle parts.

18. TIPPER A tipper truck, also known as a dump truck, is a heavy-duty vehicle designed to transport and unload loose materials such as sand, gravel, coal, and construction debris. It features a hydraulically operated tipping bed that allows for quick unloading by tilting the cargo body.

19. Types of Tipper Trucks A dump trailer connected to a prime mover via a fifth-wheel coupling. Semi-Trailer Tipper Features a clamshell-style opening at the bottom for controlled unloading. Bottom Dump Truck Used in mining and rough terrain applications, with a flexible joint between the cab and the dump body. Articulated Tipper (Off-Road Dump Truck) The truck bed tilts backward to unload material. Standard Tipper (Rear Dump Truck) The truck bed tilts to either side for unloading. Side Tipper (Side Dump Truck) The truck bed can tilt in three directions (rear, left, and right). Three-Way Tipper

20. Construction Details of a Tipper Truck Chassis & Frame – Made of reinforced high-tensile steel to withstand heavy loads. Box-section or ladder-frame design for extra durability. Tipping Mechanism (Hydraulic System) – Hydraulic Cylinder – Uses pressurized fluid to lift the truck bed. Hydraulic Pump – Powered by the engine to control lifting. Control Valve & Reservoir – Regulates hydraulic pressure. Cargo Body (Tipper Box) – Material: Made of steel or aluminum for strength and lightweight performance. Reinforced Side Walls: Prevents deformation under heavy loads. Tailgate Mechanism: Hinged for easy opening when tipping. Suspension & Axles – Heavy-duty leaf spring or air suspension to handle rough terrain. Multiple axles for better load distribution and stability.

21. Applications of Trailers Construction Sites – Transporting sand, gravel, and concrete materials. Mining Industry – Carrying coal, ores, and minerals. Waste Management – Moving bulk waste and demolition debris. Roadwork & Infrastructure – Transporting asphalt and road-building materials.

22. TANKER A tanker truck is a specialized vehicle designed to transport liquids, gases, and bulk dry goods. It features a cylindrical tank body mounted on a chassis, with safety and pumping systems for loading and unloading.

23. Types of Tanker Trucks Transports hazardous chemicals, acids, and industrial liquids. Chemical Tanker Used for LPG, LNG, or other pressurized gases. Gas Tanker Carries cement, flour, or other powdered materials. Dry Bulk Tanker Transports petroleum products (diesel, gasoline, jet fuel). Fuel Tanker Used for drinking water supply, firefighting, or irrigation. Water Tanker Made from stainless steel for hygiene compliance. Milk & Food-Grade Tanker

24. Types of Tankers Based on Bulkheads Bulkheads are internal partitions inside a tanker that provide structural integrity, safety, and stability by controlling the movement of liquids or dry bulk materials. Based on bulkhead design, tankers can be classified as follows: Fully Bulkheaded Tankers Partially Bulkheaded Tankers (Baffled Tankers) Unbulkheaded (Smooth Bore) Tankers

25. Fully Bulkheaded Tankers Contain multiple solid bulkheads dividing the tank into separate, sealed compartments. Each compartment holds a different type of liquid or reduces load shifting. Common in multi-product fuel tankers, milk tankers, and chemical transport tankers. Advantages: Prevents mixing of different liquids. Allows transportation of different products in one trip. Reduces liquid sloshing, improving vehicle stability.

26. Partially Bulkheaded Tankers (Baffled Tankers) Feature perforated or slotted bulkheads that allow limited movement of liquid between compartments. Common in milk, water, and food-grade liquid tankers to maintain stability while preventing full liquid sloshing. Advantages: Controls liquid movement while maintaining some flow between compartments. Reduces surge effect during braking and acceleration. Used when carrying only one type of liquid but needing motion control.

27. Unbulkheaded (Smooth Bore) Tankers Have no internal bulkheads or baffles, providing a single, open compartment. Used for high-viscosity liquids (e.g., molasses, asphalt, liquid chocolate) that do not move as easily. Advantages: Avoids contamination risks when switching between different liquid loads. Suitable for specialized liquids that do not require surge control. Disadvantages: High risk of liquid surge, making braking and maneuvering difficult. Less stable compared to baffled or bulkheaded tankers.

28. Construction Details of a Tanker Truck Tank Body – Material Aluminum: Lightweight, used for petroleum transport. Stainless Steel: Corrosion-resistant, used for food-grade and chemical transport. Carbon Steel: Heavy-duty, used for industrial liquids. Shape: Cylindrical or elliptical to maintain stability and prevent liquid sloshing. Compartments Single Compartment: Used for uniform loads like water. Multi-Compartment: Separate sections to carry different liquids in one trip. Loading & Unloading System – Top Loading: Fill openings on the top, often with vapor recovery systems. Bottom Loading: More efficient and safer, reduces vapor emissions. Pumping System: Uses pumps and hoses for controlled discharge.

29. Construction Details of a Tanker Truck Safety Features – Baffles: Internal partitions that reduce liquid movement (sloshing). Pressure Relief Valves: Prevents overpressure buildup inside the tank. Emergency Shut-Off Valves: Stops leaks in case of an accident. Spill Containment System: Reduces environmental risks in case of leaks. Chassis & Suspension – Reinforced chassis to handle the tank’s weight. Air or leaf spring suspension for stability on different terrains.

30. Applications of Tanker Trucks Fuel Distribution – Transporting gasoline and diesel to gas stations. Chemical Transport – Moving hazardous and industrial chemicals safely. Milk & Food Transport – Ensuring hygiene in dairy and liquid food supply. Water Supply & Firefighting – Delivering water to remote areas and fire emergencies. Gas Transportation – Carrying pressurized LPG and LNG.

31. Dimensions of driver seats S.No PARAMETER STANDARD DIMESIONS 1 Seat Height (from floor) 400–600 mm 2 Seat Depth (cushion length) 450–550 mm 3 Seat Width 450–550 mm 4 Backrest Height 600–850 mm 5 Backrest Inclination 15°–25° 6 Lumbar Support Height 150–250 mm 7 Headrest Height 750–900 mm 8 Seat Travel (Adjustment Range) 150–250 mm forward/backward

32. Relation of Seat to Controls Pedal Position (Brake, Clutch, Accelerator) Pedal distance from seat: 600–800 mm Pedal height from floor: 100–200 mm Leg angle when pressing pedals: 110°–130° Dashboard & Control Panel Distance from seat: 300–600 mm Instrument cluster visible within a 30° line of sight Button and switch reach: Within 400–500 mm from seat position Steering Wheel Position Distance from driver’s seat: 350–450 mm Adjustable tilt: 20°–30° Adjustable reach: 50–100 mm Gear Shift Lever Distance from seat: 200–400 mm Positioned within arm’s reach (~500 mm from steering centerline) Height: 600–850 mm from floor level

33. Adjustability & Comfort Features Adjustable Seat Position (forward/backward movement) Height & Tilt Adjustment (for different driver heights) Cushioned & Contoured Design (reduces fatigue) Armrests & Lumbar Support (for long-duration driving) Suspension Seats (for heavy vehicles) – Reduces vibrations on rough roads

34. Drivers Cab Design Based on Positioning Conventional Cab (Bonneted Cab)Engine placed in front of the driver . Used in trucks and heavy-duty vehicles for better crash protection . It is also known as normal control. Cab-Over-Engine (COE) Driver sits above the engine for better visibility . Common in city delivery trucks and European-style trucks. It is also known as forward control with lowered engine. Forward control with under floor engine If the engine located under the floor, the result is a suspicious cab with the sources of noise and heat eliminated. In addition , such a cab structure is much simpler as the more complicated floor and engine bonnet are avoided. Semi-Forward Cab It partially extends over the engine, balancing visibility and comfort. The driver’s cab in commercial vehicles is designed with ergonomics, safety, comfort, and functionality in mind. The layout and structure ensure that drivers can operate the vehicle efficiently while reducing fatigue and improving visibility.

35. (B) Based on Structural Design – Chassis Cab – A separate cabin with an open chassis for mounting different cargo bodies. Integral Cab (Monocoque) – The cab and body are built as a single unit, common in vans. Forward-Control Cab – Maximizes cargo space by placing the cab over the front axle. Driver’s Cab Design for Light Commercial Vehicles (LCVs) (A) Based on Cab Configuration – Standard (Single) Cab – Two-seater or three-seater with a basic cargo area. Crew Cab (Double Cab) – Additional rear seats for extra passengers. Cab-Over-Engine (COE) – Driver sits above the engine for a compact design (common in vans). Extended Cab – Extra seating space but no full rear doors. Light Commercial Vehicles (LCVs) include pickup trucks, delivery vans, and small trucks used for urban and short-haul transportation. Their cab design focuses on ergonomics, safety, visibility, and comfort to ensure efficient operation and reduced driver fatigue.

36. SLEEPER CAB DESIGN FOR COMMERCIAL VEHICLES Basic Sleeper Cab (Short-Haul Sleeper) Standard Sleeper Cab (Mid-Roof Sleeper) High-Roof Sleeper (Luxury Sleeper) Small resting area behind seats. Minimal facilities (foldable bunk, basic storage). Used for medium-distance transport. Larger sleeping space with extra headroom. Includes a single bed, climate control, and storage. Used in regional freight transport. Full-standing height with additional amenities. Includes a larger bed, workspace, mini-fridge, microwave & entertainment system. Used in long-haul trucking and international freight transport. A sleeper cab is a specially designed truck cabin that includes a resting or sleeping area for drivers, primarily used in long-haul trucking. It enhances driver comfort, reduces fatigue, and improves efficiency during extended journeys.

37. Advantages of Sleeper Cabs Reduces driver fatigue, improving road safety. Increases efficiency by allowing drivers to rest without stopping at hotels. Enhances driver comfort for long-distance routes. Saves costs on accommodation for trucking companies.

38. Unification of Dimensions in Driver’s Cab & Sleeper Cab Design The unification of dimensions refers to standardizing cab dimensions to ensure ergonomics, safety, and compatibility across different vehicle types. This is crucial for driver comfort, ease of control access, and vehicle efficiency.

39. Standardized Dimensions for Driver’s Cab Seating & Control Layout (Ergonomics) Seat Height from Floor: 400–500 mm Seat Adjustment Range: 150–250 mm (Fore & Aft) Steering Wheel Tilt Angle: 20°–30° Legroom (Pedal to Seat Back): 800–1000 mm Dashboard Reach Distance: 600–700 mm Visibility & Safety Considerations Windshield Inclination: 30°–40° (for aerodynamics) Side Window Height: 900–1200 mm (for clear visibility) Rear Mirror Placement: Standard ISO 16505 positioning Door Width: 700–900 mm (easy entry/exit)

40. Standardized Dimensions for Sleeper Cabs Sleeping Area & Comfort Features Bed Length: 1800 – 2200 mm (accommodating various driver heights). Bed Width: Standard Sleeper: 700 – 800 mm Luxury Sleeper: 900 – 1100 mm Cab Height: Low Roof: 1600 – 1800 mm Mid Roof: 1800 – 2000 mm High Roof: 2100 – 2500 mm Storage & Utility Dimensions Overhead Storage Height: 300 – 500 mm Under-Bed Storage Depth: 250 – 400 mm Refrigerator Space: 400 × 500 mm (for mini fridge). Workspace/Table Area: 500 × 600 mm

41. Benefits of Unifying Dimensions Improved Driver Comfort – Ergonomic seating & control placement. Standardized Manufacturing – Easier production & assembly across brands. Enhanced Safety – Better visibility, accessibility & crash protection. Cross-Compatibility – Easy replacement of parts & accessories.

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