sulky plow(Sulky is used adjectively in the names of several agricultural machines drawn by horses to denote that the machine is provided with wheels and a seat for the driver; as, sulky plow; sulky harrow; sulky rake, etc. [1913 Webster])
castor(Источник: MacDon Industries Ltd. Winnipeg, Manitoba, Canada. Пример: The wheels are mounted on conventional castors which swivel about a castor pin. CSB)