Truck Acceleration

Topics related to Vehicle Specifications, Vehicle Acceleration Tests, Vehicle Braking Tests
MSI
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Truck Acceleration

Post by MSI »

In response to questions on Truck/Tractor Trailer acceleration, this thread will include papers as we come across them.
these papers are in no particular order.

Low Speed Acceleration of the Freightliner FLD-120 Tractor Truck
  • SAE Paper 1999-01-0092
    Grimes, W. and Dickerson, C.
    Abstract:
    • The time/distance relationship for a heavy truck starting from a stopped position is often needed to accurately assess the events leading up to a collision. A series of tests were conducted to document the low speed acceleration performance of a Freightliner FLD-120 tractor truck. The tests including several load configurations and acceleration rates. The vehicle was instrumented with a DATRON speed sensor and the engine RPM was also documented. This paper presents data from these tests and discusses low speed acceleration profiles of heavy trucks.
"Low Speed Acceleration of the Kenworth T600 Tractor Truck,"
  • SAE Paper 98-0366
    Grimes, W. and Dickerson, C.,
    Abstract:
    • The time/distance relationship for heavy trucks starting from a stopped position is often needed to accurately assess the events leading up to a collision. A series of tests were conducted to document tractor/trailer low speed acceleration performance. The vehicles were instrumented with a DATRON speed sensor and engine RPM was also documented. This paper presents the data from these tests and discusses the acceleration profile of heavy trucks in general.
Low-Speed Acceleration of a Kenworth T2000 Tractor-Truck with Autoshift Transmission
  • SAE Paper 2000-01-0470
    Grimes, W. and Dickerson,C.
    Abstract:
    • The time/distance relationship for a heavy truck starting from a stopped position is often needed to accurately assess the events leading up to a collision. A series of tests were conducted to document the low speed acceleration performance of a Kenworth T2000 tractor- truck equipped with an auto-shift transmission. The tests included several load configurations and acceleration rates. The vehicle was instrumented with a DATRON speed sensor to measure time, distance and speed. This paper presents data from these tests and discusses low speed acceleration profiles of heavy trucks.
Acceleration Performances Testing and Simulation of Various Types of Commercial Vehicles for Railway Crossing Design
  • SAE Paper 2006-01-3458
    Bellavigna, O. and Gou, M
    Abstract:
    • As part of a study commissioned by Transport Quebec aimed at evaluating the impact of commercial vehicles on the safety of railway crossings, the acceleration performances of various heavy vehicles (buses, straight trucks and tractor-trailer combinations) was measured. The goal of these tests was to identify the typical worst acceleration performances of classes of commercial vehicles used in the calculations of sight triangles at railway crossings.
      A total of 21 commercial vehicles were subjected to testing on test track facilities and on nine railway crossings representing typical configurations found in North-America. Results were used to develop a heavy vehicle acceleration mathematical model according to the vehicles' technical specifications. The acceleration performances were then combined with various criteria associated with driver perception-reaction times, and also driver performance and skill during gear shifting. Safety factors were also applied to driver performances in order to better reflect real world situations.
      The overall typical performances obtained were used to calculate the railway crossing minimum sightline distances or sight triangles, according to the class of commercial vehicle, the safe clearance distance over the crossing, the possibility of changing gears, and also the roadway profile on the approach and exit of the crossing. This procedure can be adapted to commercial vehicles of all configurations, weights and dimensions, all operational characteristics, all road conditions, and all train and vehicle speeds, under normal weather conditions. This tool thus permits the calculation of sight triangles and integrates well into Transport Canada' RTD 10 Grade Crossing Regulations.

Low Speed Acceleration of Tractor-Semitrailers Equipped with Automated Transmissions
  • SAE Paper 2012-01-0597
    Drew, K., Van Nooten, S., and Gervais, J.,
    Abstract:
    • The distance, velocity and acceleration characteristics versus time of heavy trucks for use in accident reconstruction have been the subject of studies by Grimes and others. To date, the majority of the research has been done using tractor-semitrailers equipped with standard transmissions. In recent years, as transmission technology has improved, automated and automatic transmissions are becoming popular on North American roadways. A series of tests were performed to document the acceleration characteristics of two different tractors, a 2007 Volvo VNL and a 2011 Freightliner Cascadia, both equipped with automated transmissions towing both empty and loaded semitrailers. The vehicles were instrumented with a Racelogic™ VBOX III GPS data-logging device that measured speed. Other vehicle parameters were logged using the recording software manufactured for the specific engine manufacturer. This paper presents the data from these tests and discusses the acceleration characteristics of heavy trucks equipped with automated transmissions. Unlike fully automatic transmissions, automated transmissions have a clutch. Most have a clutch pedal but the clutch pedal is only utilized when the vehicle is first put in motion.
Analysis of Acceleration in Passenger Cars and Heavy Trucks
  • SAE Paper 95-0136
    Proctor, C., Grimes, W., Fournier, D., Rigol, J
    Abstract:
    • When analyzing the time/distance performance of vehicles accelerating from a stopped position, a constant acceleration rate is often assumed. Acceleration profiles as a function of time are examined in this paper in order to identify errors associated with the constant acceleration assumption for a passenger car and a large truck. The paper also includes acceleration data collected from 219 large trucks measured over distances of 50 and 100 feet. For passenger cars, the assumption of constant acceleration is appropriate when evaluating velocity/distance scenarios with displacements of interest greater than 10 ft. For 5 ft or less, variable acceleration is recommended. When time factors are of special interest, attention must be given to the lag times associated with variable acceleration. The lag time does little to affect the velocity/distance relationship; however, it alters time/distance/velocity relationship by as much as 2 seconds. For heavy trucks, a speed surge is seen immediately before shifting from 2nd to 3rd gear, but due to the low acceleration values, little impact is seen in the time/distance profile. The constant acceleration assumption for heavy trucks appears valid for situations where the driver is shifting. In these tests the approximate constant acceleration was 0.07 g's. When the driver of a heavy truck does not shift, the transmission gearing as well as the weight of the load is important in determining the acceleration of the vehicle. When a heavy truck is not shifted, using constant acceleration 0.05 g's usually under-estimates the distance traveled in the 4-8 second range and over-estimates the distance traveled after 8 seconds. Based on the time and distance measurements for the 219 trucks, calculated average accelerations were 0.085, 0.106, and 0.138 g's over the first 50 ft for the flatbed, box, and bobtail configurations, respectively. Over a distance of 100 ft, the average accelerations were somewhat lower: 0.064, 0.073, and 0.118 g's for the flatbed, box, and bobtail configurations, respectively.
Heavy Fire Apparatus Acceleration and Braking Performance
  • SAE Paper 2010-01-0112
    English, J., Beck, R., and Casteel, D.
    Abstract:
    • Evaluating pre-impact acceleration and braking is an important aspect of reconstructing collisions. These performance characteristics are well documented for many vehicle classes, but are limited when discussing modern fire apparatus designs. These vehicles are engineered to be well-balanced, but are typically heavy due to the amount of equipment and fluids onboard. Manufacturers have basic production designs that serve as the platform for custom specification orders from the end-user.
      The emergency driving conditions in which they operate constantly challenge the vehicle components, including the brake systems. Because of the heavy weights and operating conditions, auxiliary brake systems are often installed to provide additional braking capabilities as well as prolong the life of the service brakes.
      A series of acceleration and braking tests were conducted using heavy fire apparatus of several classifications. Braking tests were conducted using the service brakes, both with and without the available installed auxiliary braking devices. Data was collected using accelerometers, video, and ground measurements. The target speed for these tests was 64 kph (40 mph).
      This paper addresses the results of these tests and previously completed similar performance tests of modern fire apparatus designs.

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