Browse Topic: Transmissions
This SAE Recommended Practice describes two-dimensional, 95th percentile truck driver, side view, seated shin-knee contours for both the accelerator operating leg and the clutch operating leg for horizontally adjustable seats (see Figure 1). There is one contour for the clutch shin-knee and one contour for the accelerator shin-knee. There are three locating equations for each curve to accommodate male-to-female ratios of 50:50, 75:25, and 90:10 to 95:5
Cooling system for an IC engine, consisting of the Water pump (WP), Radiator and Fan, plays an important role in maintaining thermal efficiency of the engine and protects the engine from overheating. Based on the vehicle application requirement, Fan will be mounted directly either on Crankshaft or WP pulley. But wherever increase in Fan speed ratio are in demand, it is preferred to mount the Fan on WP pulley. So it important to understand the WP housing structural strength with respect to vibration loads contributed from Radiator Fan assembly. This paper presents investigation of Failure of WP Housing during engine validation at engine test bed with Electronic Viscous Fan, based on the different operating conditions of the engine and fan as per the validation cycle. While the accessories are loading and the corresponding stresses are high when the fan is engaged. But in the current case, the failure of WP housing happened only during Fan clutch disengaged condition. Experimental
The stiffness and positioning of engine mounts are crucial in determining the powertrain rigid body modes and kinetic energy distribution. Therefore, optimizing these mounts is essential in the automotive industry to separate the torque roll axis (TRA) and minimize vibration. This study aims to enhance mount locations by isolating the engine rigid body modes and predicting the inter-component force (ICF) and transfer function of the vehicle. The individual ICFs for engine mountings are calculated by applying a unit force at the bearing location. Critical frequencies are identified where the amplification exceeds the unit force at the mounting interface between the engine and the frame. The transfer function approach is utilized to assess the vibration at the handlebar. Both ICF and transfer functions analyze the source and path characteristics linked to critical response frequencies. This understanding aids in enhancing mounting positions to minimize vibration levels, thereby enhancing
Clutch wear is a significant factor affecting vehicle performance and maintenance costs, and understanding its dynamics is crucial for original equipment manufacturers (OEMs) to enhance product reliability and customer satisfaction. It is important to predict clutch wear to enable customers to understand the condition of their clutch and the remaining clutch life, to avoid sudden vehicle breakdowns. This paper explains the approach of measuring the clutch wear profile on an actual vehicle and simulating the same conditions on a powertrain test bench, with the establishment of a correlation in clutch wear profiles
Gear shifting effort or force especially in manual transmission has been one of the key factors for subjective assessment in passenger vehicle segment. An optimum effort to shift into the gears creates a big difference in overall assessment of the vehicle. The gear shifting effort travels through the transmission shifting system that helps driver to shift between the different available gears as per the torque and speed demand. The shifting system is further divided into two sub-systems. 1. Peripheral system [Gear Shift Lever with knob and shift Cable Assembly] and Shift system inside the transmission [Shift Tower Assembly, Shift Forks, Hub and sleeve Assembly with keys, Gear Cones and Synchronizer Rings etc.] [1]. Both the systems have their own role in overall gear shifting effort. There has been work already done on evaluation of the transmission shifting system as whole for gear shifting effort with typical test bench layouts. Also, work has been on assessment of life of the
The future of wireless technology - from charging devices to boosting communication signals - relies on the antennas that transmit electromagnetic waves becoming increasingly versatile, durable and easy to manufacture. Researchers at Drexel University and the University of British Columbia believe kirigami, the ancient Japanese art of cutting and folding paper to create intricate three-dimensional designs, could provide a model for manufacturing the next generation of antennas. Recently published in the journal Nature Communications, research from the Drexel-UBC team showed how kirigami - a variation of origami - can transform a single sheet of acetate coated with conductive MXene ink into a flexible 3D microwave antenna whose transmission frequency can be adjusted simply by pulling or squeezing to slightly shift its shape
ABSTRACT Traditional engineering concerns such as lubrication and cooling are still present even as vehicle functions become more complex. The established solution to monitor fluid levels has been a sight glass or a dipstick. More complex machines demand continuous knowledge of fluid levels without adding to operator workload. Remote monitoring of vehicle health will become normal and expected by owners and operators of evolving vehicle designs. This dual function fluid level sensor provides both electronic and operator monitoring of vehicle fluids, as well as redundancy in the event of electronic failure. Grouping of sensor components that are considered more likely to fail into one group, aids replacement when necessary. By incorporating a traditional dipstick into a continuous electronic monitoring solution, either method of level monitoring is facilitated
ABSTRACT Variable displacement pumps have been used in automotive transmissions for decades. L3T had high confidence that a Variable Displacement Oil (VDO) pump would increase overall transmission efficiency. An off-the-shelf (OTS) or OTS modified pump in this pressure and flow range was not found. Therefore, a VDO pump is being developed with the known risk of replacing a highly reliable pump with a new better performing pump of unknown reliability. In this document the development of this VDO pump is discussed. Initial testing of the VDO pump demonstrated an average 25HP savings in pumping losses throughout the transmission operating ranges. At this point, durability testing has not been performed
ABSTRACT The recent climate change plan for the United States Army states that hybridized combat vehicles will enter the fleet by 2050. The Bradley Fighting Vehicle (BFV) and its family of vehicles are prime candidates for hybridization. This paper sets out to perform a drive cycle analysis for the BFV using its traditional powertrain along with hybridized powertrains. The analysis considers both series and parallel hybrid architectures, where the size of the batteries are based on modifications to the existing powertrain. Three different drive cycles are considered – stationary, highway, and off-road. The model accounts for accelerative forces, transmission losses, cooling losses, drag, road grade, tractive losses, and ancillary equipment. The results indicate that both parallel and series hybrids provide reduced fuel consumption and increased range. Of the two, the series hybrid architecture provides more overall benefits. The study concludes by discussion of the technical challenges
ABSTRACT The HMPT500-3 is a split torque path hydrostatic / mechanical continuously variable transmission used in the Bradley Fighting Vehicle. Power transmission and steering is accomplished through the interaction of six planetary gear sets and two variable displacement hydrostatic pump / motor units (HSUs). Power flow in the HMPT500-3 is extremely complex, with numerous feedback paths within the planetary gear train. Without a clearly defined power flow path from gear set to gear set, the analysis cannot be handled in the conventional stepwise manner. The complete speed and torque equation sets must be solved simultaneously for all components. A linear algebraic approach was developed to model forward operation of the HMPT500-3 without steering. The left and right HSUs are lumped in a single unit, and the steering differential is ignored. A reduced set of 14 simultaneous equations for speed and 14 simultaneous equations for torque enable modeling of the ideal (lossless) power flow
ABSTRACT Thermal management systems (TMS) of armored ground vehicle designs are often incapable of sustained heat rejection during high tractive effort conditions and ambient conditions. The use of a latent heat energy storage system that utilizes Phase Change Materials (PCMs) is an effective way of storing thermal energy and offers key advantages such as high-energy storage density, high heat of fusion values, and greater stability in temperature control. Military vehicles frequently undergo high-transient thermal loads and often do not provide adequate cooling for powertrain subsystems. This work outlines an approach to temporarily store excess heat generated by the transmission during high tractive effort situations through use of a passive PCM retrofit thereby extending the operating time, reducing temperature transients, and limiting overheating. A numerical heat transfer model has been developed based around a conceptual vehicle transmission TMS. The model predicts the
Abstract This paper presents the development of a transmission-in-the-loop (TiL) experimentation system. In this TiL experimental setup, the input side of the transmission is controlled by a dynamometer emulating the engine, while the output sides of the transmission are controlled by two dynamometers emulating the wheels and vehicle. The models emulating these vehicle components are required to possess sufficient fidelity to simulate engine torque pulse (ETP) and wheel slip dynamics while being computationally efficient to run in real-time. While complex engine and tire models exist in the literature that accurately capture these dynamics, they are often too numerically stiff for real-time simulation. This paper presents the system level details of such a TiL setup, and the modeling concepts for the development of high fidelity real-time models of the engine and tire dynamics for use in this experiment. Parameters of the engine model are identified using experimental data. Vehicle
WHY DO WE NEED SIMULATIONS? This paper is intended to provide a broad presentation of the simulation techniques focusing on transmission testing touching a bit on power train testing. Often, we do not have the engine or vehicle to run live proving ground tests on the transmission. By simulating the vehicle and engine, we reduce the overall development time of a new transmission design. For HEV transmissions, the battery may not be available. However, the customer may want to run durability tests on the HEV motor and/or the electronic control module for the HEV motor. What-if scenarios that were created using software simulators can be verified on the test stand using the real transmission. NVH applications may prefer to use an electric motor for engine simulation to reduce the engine noise level in the test cell so transmission noise is more easily discernable
ABSTRACT The following paper describes the new SAPA automatic transmissions for the future military vehicles. The very high mobility requirements, the reclaim of weight, power & space and the actual relevance of the fuel consumption require a rethinking and a new vision of the automatic transmission concept and design. This is what SAPA has been working on for the last 12 years obtaining excellent technical and commercial results, a concept aimed at reducing the power losses of the conventional powershifting transmission eliminating the torque converter, reducing the spin losses -due to hydraulic pumps and friction discs-, and improving vehicle mobility on variable terrain situations as off-road
ABSTRACT L-3 Combat Propulsion Systems (L-3CPS) and Kinetics Drive Solutions (Kinetics) have teamed together to present this paper that discusses infinitely variable transmission technologies with high gear ratio & efficient steering systems for cross-drive transmissions across a family of combat vehicles. Traditionally, cross-drive transmissions for tracked vehicles are very rigid systems, which are tailored for a specific application or vehicle weight class. This becomes a problem throughout the vehicle’s lifecycle, as vehicle weights continue to grow when armor and other systems are added to protect and support the war-fighter. Increased weight leads to degraded vehicle mobility performance. To regain the vehicle mobility performance more power is needed at the vehicle sprockets. Traditionally this is accomplished by increasing the engine power of the propulsion system, which requires an increased transmission size for higher input and output torques, resulting in increased losses
ABSTRACT The paper presents the EMX Hybrid Electric Cross Drive transmission developed by Kinetics Drive Solutions to satisfy RCV as well as conventional tracked vehicle requirements. Key design characteristics are modularity to enable performance customization, scalability to suit various vehicle weight classes, and flexibility to adapt to latest advancements in electric motor/inverter technology and autonomous control. EMX1000 prototypes have been built and are currently undergoing testing on dyno as well as in vehicle. Future development includes refining the prototype design and scaling the design for a heavier weight class. Citation: Caldarella F., Johnson A., Wright G., Scheper R., “Development of a Modular and Scalable Hybrid Electric Cross Drive Transmission,” In Proceedings of the Ground Vehicle Systems Engineering and Technology Symposium (GVSETS), NDIA, Novi, MI, Aug. 16-18, 2022
Due to the compact structure of the Bacha Racing vehicle, the continuously variable transmission (CVT) serves as a crucial transmission component. It is essential to tune and verify its performance to ensure the power matching and transmission efficiency of the entire vehicle. This paper conducts a kinematic analysis of CVT based on transmission theory, designs real vehicle traction experiments, and CVT bench tests. Additionally, it proposes a method to utilize Hall sensors for real-time monitoring of CVT motion to assist in its tuning. The results demonstrate that the optimal performance tuning of the CVT for the Bacha Racing vehicle has been achieved through various experiments
A well-designed cooling system is crucial in construction machines for efficient heat dissipation from vital components, including the Radiator(RAD), Oil Cooler (OC) and Intercooler (IC). The radiator ensures optimal engine performance and longevity by maintaining a stable operating temperature. Oil Coolers preserve hydraulic system efficiency. Inter Coolers optimize engine performance through denser intake air. The robust cooling system enhances system reliability, reduces downtime, avoid overdesigned system, and increases operator safety in demanding construction environments. The size and location of heat exchangers are critical in cooling system design. Using 1D simulation tool KULI for cooling system design offers the benefits of comprehensive system simulation, optimization of thermal management, reduced development time and costs, enhanced system reliability, improved integration with other systems, and real-world testing and validation. The tool enables time and cost-effective
In conventional vehicles the shift strategy has a well-known impact on the system’s efficiency. An appropriate gear choice allows the internal combustion engine (ICE) to operate in efficient operating points (OPs) and thus contributes significantly to a reduced fuel consumption. Further efficiency improvements can be achieved by the hybridization of the powertrain. Due to the two propulsion systems, an additional degree of freedom arises, that requires an energy management strategy (EMS). The EMS controls the split of the requested power between the electric machine (EM) and the ICE. Accordingly, the system’s overall efficiency in hybrid electric vehicles (HEVs) is highly influenced by the quality of the EMS. This paper proposes to adapt an existing method for deriving fuel-optimal rule-based EMS by including the shift strategy for parallel HEVs. It is shown that fuel-optimal control can be achieved. The analytically derived look-up tables can be used to automatically calibrate in
The purpose of this SAE Recommended Practice is to provide guides toward standard conditions for operating marine hydraulic transmissions where push-pull cable control is applicable. For control cable information see SAE J917
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