TW 501 – Powertrain Control Systems

Duration : 20 Hours

Content :

The purpose of this workshop is to teach the fundamentals and current state of art in powertrain components and their computer control, with focus on construction equipment applications.  Included in the workshop are the following components: engine, transmission, brakes and traction control, suspension and axles, steering, hydraulic system and cooling system.  The workshop is coordinated by one instructor, and delivered by a group of instructors, each with an expertise in each component or sub-system.

  1. Overview of powertrain in construction equipment applications:
    • Basic machine “skeleton”: how is it built ground up.  Mechanical design, their operating principles.
    • Vehicle frame, suspension, and axels and final drive.
    • Description of each basic component (engine, transmission, lower powertrain, steering and implement hydraulic system, brakes system, cooling system etc) and their interconnectivity in terms of power flow and controlled elements.   The discussions will follow the following approach: pictures and drawings of the components, circuit diagrams of the sub-systems made of connected components, controlled elements and embedded sensors.
    • Options for active control: i.e. active suspension (involving hydro-mechanical or electrohydraulic controls) versus passive suspension (not involving any computer controls, but thru hydro-mechanical design).
  2. Diesel engine:
    • Basic operating principles of diesel engineers: pictures, cross sections of diesel engine, hands-on discussions at an engine factory with engine cross-section as well as visiting the assembly line.
    • Controlled components in the diesel engine and current technological challenges:
      1. Fuel injection timing, amount and pattern,  turbo-charging, engine braking (compression and exhaust braking), ATAAC. Basic engine performance: steady-state lug curves, dynamic response, emission issues.
    • Engine control:  objectives for Tier 3 and Tier 4, sensors (currently used and possibly to be used), controlled components and their dynamic response characteristics (repeatability, bandwidth, calibration on commissioning and overtime)
    • Engine control algorithms and various “electronic governor” concepts: min-max governor, partial throttle governor, and others.
  3. Transmission:
    • Basic operating principles of:  direct drive transmissions,  torque-convertor plus planetary gear type transmissions (including lock-up clutch and neutralized clutch), continuously variable transmissions (PPV), hydrostatic transmission (pump-motor combinations).   Retarder built into the transmission.  Pictures, cross section drawings, see first hand at the factory floor.
    • Controlled components and sensors (including the signal type: ON/OFF, proportional (PWM or Analog Current or Analog Voltage), summarized as a table of inputs and outputs from controller perspective, each component is characterized in terms of its repeatability and dynamic response.
    • Transmission automatic gear shifting strategies: engagement and disengagement pressure control of clutch and brakes, lock up clutch control, hydraulic retard control.   Current and future “integrated transmission control strategy concepts” based on the condition of engine and traction and operator commands.
  4. Lower Powertrain: Brakes, Differentials, Final Drive and Propeller Shafts.
    • Basic operating principles of brakes:  dry and wet type multi-disc brakes (pictures, cross-section drawings, hands on review at the factory), service brakes and parking brakes.   Lock-up and proportionally  controlled differentials.  Final drive geometry, propeller shaft and its dynamic considerations.
    • Brake control system hydraulic and electro-hydraulic circuit diagrams:  power sources, back-up circuits and safety, brake cooling system.
    • Comparison of hydro-mechanical brake control systems with electro-hydraulic brake control systems, traction control, anti-lock braking systems (ABS), dynamic stability control.
  5. Steering and Hydraulic Systems:
    • Steering mechanics, especially articulated steering; hydro-mechanical steering systems in construction equipment applications (HMU and CCS steering and examples from other competitors)
    • Hydraulic circuits: primarily used ones – open-center systems, load sensing systems, pressure compensated systems and comparisons.
    • Hydro-mechanical and electro-hydraulically controlled steering and tool-hydraulics, implications for machine performance controllability and customization.
    • List of controlled elements, sensors used, typical control algorithms in EH systems.
  6. Cooling System:
    • Engine cooling
    • Brake cooling
    • Hydraulic oil cooling
    • Cab heating and air conditioning systems and their controls