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Technical Writing Basics
Published in Phillip A. Laplante, Technical Writing, 2018
A brake retarder is a device used on large trucks to slow the engine, thus slowing the vehicle. Brake retarders are very noisy, and, as a result, many municipalities prohibit their use within city limits. Let’s have a little fun with the sign. If we substitute the synonyms:
Air and endurance brake systems
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
During normal driving when braking is not required the retarder is empty of oil, but when it is brought into operation, typically by initial depression of the normal brake pedal, the braking effect can be closely controlled according to the amount of oil admitted to the retarder via a pneumatically actuated valve. To dissipate the heat being generated by the retarder, arrangements are made for the fluid in circulation to be passed through either a heat exchanger in the engine cooling system, or a separate oil-to-air heat exchanger in the case of an air-cooled engine. The main advantage of the hydraulic retarder is that it develops a much greater braking effect than other types, and especially from high speeds. In common with other drive line retarders it still remains effective in the event of an engine failure or a missed downward gear change.
Dynamics performance of long combination vehicles with active control systems
Published in Vehicle System Dynamics, 2023
Wei Huang, Mehdi Ahmadian, Amir Rahimi, Luke Steiginga
Another non-emergency means of braking is a hydraulic retarder, such as is shown in Figure 19, which can reduce the use of service brakes and the resultant brake fade performance issues. The accurate calculation of the hydraulic retarder brake torque for improving heavy vehicle stability and dynamic performance in downhills is studied in [103]. A fuzzy PID speed control methodology is proposed to manipulate the hydraulic retarder and keep the vehicle running at a constant speed in downhills with various slopes. The controller efficiency is then compared with a conventional PID controller through simulations. The fuzzy PID speed controller yields a smaller overshoot, faster adjustment time, better steady-state response, and more robust performance in the presence of road grade disturbances.
Economic benefits of load volume scanning of underground mining trucks
Published in CIM Journal, 2023
The productivity of truck haulage systems is measured by the average payload divided by the cycle time. Cycle times are calculated from the cumulative sum of the times involved in a sequence of actions. First, the unloaded truck enters the portal and trams down the decline to the loading location. Blasted material is removed from the stope via a load-haul-dump vehicle and loaded into the truck tray in a series of dumps or passes. Finally, the loaded truck proceeds back up the decline, exiting the portal to dump material at the run-of-mine stockpile (Figure 1). In order to optimize productivity, truck payloads should not exceed a recommended 10% above the rated payload. Overloaded trays cause trucks to be slower on the decline, extending cycle times and increasing fuel consumption. Underloaded trucks are associated with an opportunity cost for not carrying correct load and CO2 emissions per tonne (t) will increase. Carry back (also known as haul back) is the material that adheres to the tray following dumping and is carried back into a mine during a return cycle. This increases truck fuel consumption and causes accelerated tire wear and the potential for hydraulic retarder brakes to overheat.
A method to assess haul roads rolling resistance using dispatch system data
Published in Mining Technology, 2021
Douglas Alegre, Rodrigo de Lemos Peroni, Eduardo da Rosa Aquino, Felipe Dille
An alternative way to determine the projected speed of trucks without using the Rimpull curves was developed by Cooper (2008). The author suggests the use of Equations (5) and (6) to calculate the expected velocity depending on the condition of the haul road (uphill or downhill) and the size and engine power of the truck: where is the gross engine power (kW), is the transmission efficiency, is the retarder efficiency, GVM is the gross vehicle mass (t), GR is the grade of the haul road (negative for downgrade and positive for upgrade) (%), and TR is the total resistance (%).