Steering knobs should NOT be used on a sit-down counterbalanced lift truck unless you h'ave something in writing from the manufacturer authorizing their use. With nothing on file, it could be considered an alteration or modification and an employer could be charged.
What you'll see in print deals with road kickback or feedback, that's why steering knobs that are in use are to be inside the diameter of the steering wheel and held palm style.
What you will not see in print is the fact a lift truck could turn that much quicker and sharper and a steering **** could be determined to be the cause or a major contributor to a lateral tip-over. If this were to happen and the employer had nothing on file from the., the employer could have a problem.
Some other issues relate to a driver not used to a steering **** and forgetting to use and he could bang his hand in a corner and lose control of the steering.
A person getting off a lift truck could catch loose clothing on a steering **** and get thrown back as they get off.
Probably one of the major issues to address is a sudden stop when traveling forward or a forward tip-over. With or without the use of a seatbelt, guess where the steering **** is going to end up.
Most lift trucks these days have power steering and anyone using a steering **** is not aware of the dangers and if they are I don't believe the employer has a defense of due diligence on this one.