Top Navigation Bar

ASAE Journal Article

Engineering Tractors for Higher Speeds

Ray Clay and Paul Hemingway

Chief Engineer, JCB Landpower Ltd. Cheadle, Staffordshire, England; and General Service Manager, JCB Sales Ltd. Rocester, Staffordshire, England


Published in ASAE Distinguished Lecture Series No. 25, pp. 1-16. February 2001 ( Copyright 2001 American Society of Agricultural Engineers ).

The ASAE Distinguished Lecture Series was prepared and presented at the Agricultural Equipment Technology Conference, 12-14 February, 2001, Louisville, Kentucky, by Ray Clay and Paul Hemingway, JCB Group, Stafforshire, England. For additional information, correspondence may be directed to: Paul Hemingway, JCB World Parts Centre, Cheadle Road, Uttoxeter, Stoke on Trent, Staffs ST 14 7BS, United Kingdom, e-mail: paul.hemingway@jcb.com


This paper examines the market demand for tractors capable of higher than normal working speeds and discusses the evolution of such tractors in the market place over the past 20 years. The key engineering issues which have to be addressed in the construction of tractors of up to 80 kph (50 mph) speed capability are discussed in detail. Particular attention is paid to the areas of vehicle ride and handling, wheel and tire technology, steering, suspension and braking systems.

To illustrate that all necessary engineering requirements can be met in a vehicle that also develops comparable off road traction to that of a similar horsepower conventional tractor, the JCB Fastrac is discussed as a case study. Particular reference is made to the way in which the key vehicle systems above have been engineered into the vehicle.

Section headings and keywords. Engineering for Higher Speed, The market place today, 30 kph (20 mph), 40 kph (25 mph), 50 kph (32 mph), Above 50 kph (32 mph), Fundamental principles, Vehicle ride, Vehicle handling, Wheel and Tire Technology, Braking force, Cornering force, Accelerating force, Steering, Slip angle, Center of pressure/Pneumatic trail, Camber angle, Kingpin or swivel inclination, Caster angle, Steering response, Suspension, Pitch attenuation, Handling, Braking Systems, Legal requirements, Tractor brakes, Trailer brakes, Case Study - The JCB FASTRAC, Suspension, Steering, Brakes.

This paper examines the market demand for tractors capable of higher than normal working speeds and discusses the evolution of such tractors in the market place over the past 20 years. The key engineering issues which have to be addressed in the construction of tractors of up to 80 kph (50 mph) speed capability are discussed in detail. Particular attention is paid to the areas of vehicle ride and handling, wheel and tire technology, steering, suspension and braking systems.

To illustrate that all necessary engineering requirements can be met in a vehicle that also develops comparable off road traction to that of a similar horsepower conventional tractor, the JCB Fastrac is discussed as a case study. Particular reference is made to the way in which the key vehicle systems above have been engineered into the vehicle.

-------------------- For the full version of this document please view the PDF. --------------------