Tuesday, 13 November 2018


When determining the chassis for a professional vehicle, the ultimate goal must be to ensure that the finished vehicle is optimized for its intended use. This process ensures a safer, more productive vehicle while minimizing total cost of ownership throughout the life cycle. Often, fleets choose a chassis for a particular application based on intuitive factors such as previous experiences, recommendations from other people or simply require guesses about the size or type of chassis. However, there is an orderly procedure that must be followed to determine the chassis requirements. Although a detailed explanation
of the frame specifications can take several hours, the procedure described here describes the basic elements. A warning prior to drafting this procedure. Fleets should view specific vehicle applications in relation to a specific specification. For example, specify a tipper that transfers abrasive or corrosive material, consider the effect of this material on the bogie housing.

How can you identify important factors?

To determine the chassis correctly, you must first

Identify a number of important factors:

           Requirements for the second unit (equipment).
           Performance criteria met for the vehicle.
           Legal and other design restrictions.

These requirements ultimately determine the final design of the finished vehicle and must therefore control the chassis specification process. After specifying the first factors, the entire design process and specifications can be divided into 10 steps. After this process, it is helpful to make sure that the finished vehicle is suitable for the desired application.

The steps described here include examples of the types of information required for each phase.

  Step 1: Determine the basic requirements of the application:

       What will the car be designed for?
       What are the performance requirements for another device?
       What is the expected duration of the application?
       What type of body of the second unit and / or special equipment is desirable?

Step 2: Specify the applicable design restrictions:

       Dimensions (width, height, length, weight).
       Operational restrictions.
       Regulatory issues.
       Contractual requirements.
       Financial restrictions.

Step 3: Specify the requirements for net pay:

       Cargo weight.
       Volume load.
       Requirements to the sizes (the size of the transported materials).

Step 4: Determine the basic special equipment / requirements of the second unit:

     Size of special equipment and / or second unit for mounting on chassis.
     Weight of equipment.
     Requirements for storage of cargo and safety.
     Component installation requirements (chassis requirements, free spacing between axles, restriction of exhaust system position, etc.).
     Operational requirements (power supplies for devices and access requirements, etc.).

 Step 5: Identify additional special devices / chassis requirements:

  Special equipment and housing requirements may include generators, hose reels, etc., as well as service bodies, unloading bodies, and others.

     Size of accessories.
     Installation requirements.

Step 6: Specify Gross Load Requirements:

     Net load
     The second block weight.
     Weight of special equipment.
     Load trailer traction (lang weight / total weight).
     Crew weight
     Fuel requirements (weight).
     Operational requirements.

Step 7: Determine the vehicle operating conditions and environment:

     Duty cycle - the percentage on the road / outside; working cycle (desired cycle time,
      daily working hours, etc.).
     Charging cycle - static or dynamic charging (affects the choice of suspension elements).
     Climate / weather.
     Notes on maintenance, including vehicle maintenance history.
 Step 8. Specify the required vehicle performance requirements:

     Starting gradation, on / off road.
     Maximum thanks.
     Keep your gratitude.
     Maximum speed on the road.
     Requirements for braking.
 Step 9: Advanced Chassis Design

     Availability of a suitable chassis: GVWR / GCWR, frame, dimensions and drive system options.
     Estimated unit weight. VERIFICATION OF SANITARY 3 By using approximate data from 
     a pre-selected chassis, make the final decision that the complete vehicle will meet all  predetermined criteria.

 Step 10: Final Chassis Specification:
 Determine the chassis, making sure that all of the most important design factors are taken into account, including:

    Full axle load does not exceed GAWR (including trailer load).
    The total weight of the vehicle does not exceed the GVWR (including trailer loading).
    The total gross weight does not exceed the GCWR (with the heaviest trailer).
    Frame selection meets or exceeds OEM requirements for chassis and equipment.
    The suspension is adapted to other requirements.
    The drive provides the desired performance (engine, transmission and main transmissions).
    Auxiliary systems, such as electrical, cooling, etc., meet or exceed certain requirements.
    Requirements for additional equipment are taken into account (power take-off rules, exhaust routes, etc.). Other non-functional aspects:

    Staff retention / performance issues (comfort and convenience).
    Resale value. Return of goods added for resale should cover the cost of maintaining the unit.
    Driver / operator skills.

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