Question Most heavy trucks with manual transmissions require ____ to change gears. Answers Single clutching Double clutching Triple clutching Quadruple clutching Explanation Most heavy vehicles with manual transmissions require double clutching to shift gears. Learning to effectively change gears by double clutching takes practice. This questions appears in the following tests: Illinois Class B Knowledge Test Maryland Class B Knowledge Test Massachusetts Class B Knowledge Test Minnesota HazMat Mississippi Class B Knowledge Test Nebraska Class B Knowledge Test Tennessee Class A Knowledge Test