Influence of Tyre Pressure and Weight Distribution on Axles on the Theoretical Speed Ratio in the Running Gear System of Four-Wheel Drive Tractors

2015 ◽  
pp. 695-701 ◽  
Author(s):  
Mircea Nastasoiu ◽  
Nicolae Ispas
Keyword(s):  
Weight Distribution ◽  
Gear System ◽  
Speed Ratio ◽  
Tyre Pressure ◽  
Wheel Drive ◽  
Four Wheel Drive

Optimization of the tractive performance of four-wheel-drive tractors: Theoretical analysis and experimental substantiation

1998 ◽  
Vol 212 (4) ◽  
pp. 285-297 ◽  
Author(s):  
J. Y. Wong ◽  
N. B. McLaughlin ◽  
Z Knezevic ◽  
S Burtt
Keyword(s):  
Theoretical Analysis ◽  
Field Test ◽  
Angular Speed ◽  
Speed Ratio ◽  
Torque Distribution ◽  
Wheel Drive ◽  
Four Wheel Drive ◽  
Tractive Efficiency ◽  
Driving Torque ◽  
Experimental Substantiation

The results of a theoretical analysis reveal that, for a four-wheel-drive tractor to achieve the optimum tractive performance under a given operating condition, the thrust (or driving torque) distribution between the front and rear axles should be such that the slips of the front and rear tyres are equal. For four-wheel-drive tractors with rigidly coupled front and rear drive axles, this can be achieved if the theoretical speed (the product of the angular speed and the free-rolling radius of the tyre) of the front and that of the rear wheels are equal or the theoretical speed ratio is equal to 1. Field test data confirm the theoretical findings that, when the theoretical speed ratio is equal to 1, the efficiency of slip and tractive efficiency reach their respective peaks, the fuel consumption per unit drawbar power reaches a minimum, and the overall tractive performance is at an optimum.

scholarly journals Mechanical Devices for Mass Distribution Adjustment: Are They Really Convenient?

Agronomy ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1820
Author(s):  
Massimiliano Varani ◽  
Michele Mattetti ◽  
Mirko Maraldi ◽  
Giovanni Molari
Keyword(s):  
Weight Distribution ◽  
Rear Wheel ◽  
Front Wheel ◽  
Original Position ◽  
Fuel Saving ◽  
Wheel Drive ◽  
Loam Soil ◽  
Mechanical Devices ◽  
Four Wheel Drive ◽  
Engine Power

Since the introduction of four-wheel drive (4WD) and especially front wheel assist (FWA), many studies have been conducted on the optimal weight distribution between tractor front and rear axles because this influences traction efficiency. The aim of this paper is to evaluate the traction and efficiency advantages in the adoption of mechanical ballast position adjustment devices. The tested device is an extendable ballast holder mounted on the front three-point hitch of the tractor, able to displace the ballast up to 1 m away from its original position. An estimation of the fuel consumption during ploughing with the extendable ballast holder in different configurations was performed. Tractive performance was evaluated through drawbar tests, performed on loam soil with a 4WD tractor having a maximum engine power of 191 kW and a ballasted mass of 9590 kg. Results show that changing the tractor weight distribution over the range allowed by the extendable ballast holder produces limited effects in terms of tractive performance and fuel saving. The adoption of such devices is thus ineffective if other fundamental factors such as tyre pressure, choice of the front-to-rear wheel combination and lead of the front wheels are not considered during tractor setup.

Tractive efficiency of four-wheel-drive vehicles: An analysis for non-uniform traction conditions

2003 ◽  
Vol 217 (5) ◽  
pp. 363-374 ◽  
Author(s):  
B C Besselink
Keyword(s):  
Mathematical Analysis ◽  
Fixed Ratio ◽  
Graphical Analysis ◽  
The Other ◽  
Speed Ratio ◽  
Road Vehicles ◽  
Wheel Drive ◽  
Four Wheel Drive ◽  
Tractive Efficiency ◽  
Rigorous Mathematical Analysis

An analysis of the tractive efficiency of four-wheel-drive vehicles is conducted from the perspective of maximizing efficiency of slip with respect to non-uniform traction conditions in particular. The analysis is conducted using a more rigorous mathematical analysis than previously and using a thorough graphical analysis to substantiate the mathematical analysis. Previous studies concluded that under all traction conditions efficiency of slip will be a maximum when the slip of each wheel is equal. The analysis revealed that, contrary to the previous literature, efficiency of slip will not be a maximum when the slip of each wheel is equal under non-uniform traction conditions. When applied to a vehicle with an interaxle fixed ratio coupling, this means that the optimum theoretical speed ratio is not always equal to 1. An example of non-uniform traction conditions is the situation where two drive wheels are on soil and the other two are on tarmac. The improvement in the efficiency of slip, in this example, when using the correct theoretical speed ratio (as opposed to that equal to 1) is particularly marked at high drawbar loads. The method by which the correct theoretical speed ratio is to be achieved when non-uniform traction conditions occur is problematic. The drive system would require a drive mechanism and a level of intelligence not currently found in off-road vehicles.

Factors contributing to the amount of vehicular damage resulting from collisions between four-wheel drive vehicles and passenger cars

2001 ◽  
Vol 33 (5) ◽  
pp. 673-678 ◽  
Author(s):  
Robert W. Broyles ◽  
S.Ross Clarke ◽  
Lutchmie Narine ◽  
Daryl R. Baker
Keyword(s):  
Passenger Cars ◽  
Wheel Drive ◽  
Four Wheel Drive
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