Researching the Craftsman walk behind front wheel drive mower, I discovered that the advertised variable speed is only achieved by allowing the drive belt to slip on the pulleys. (Mower models 37066 and 37041).
http://www.searspartsdirect.com/partsdirect/part-model/Craftsman-Parts/Walk-behind-lawn-mower-Parts/Model-917370660/0247/1500600/1105087P/00002?blt=06&prst=0&shdMod=917370660
The front wheel drive just has a belt from the motor to a pulley that's mounted on the vertical to horizontal gear box at the front of the mower. The gear box and pulley pivot on the horizontal rods that go to the tires. The pivoting action tightens or loosens the belt. So the variable speed is only achieved by letting the belt slip on the pulleys.
How does variable speed work on other brands of front wheel drive mowers?
http://www.searspartsdirect.com/partsdirect/part-model/Craftsman-Parts/Walk-behind-lawn-mower-Parts/Model-917370660/0247/1500600/1105087P/00002?blt=06&prst=0&shdMod=917370660
The front wheel drive just has a belt from the motor to a pulley that's mounted on the vertical to horizontal gear box at the front of the mower. The gear box and pulley pivot on the horizontal rods that go to the tires. The pivoting action tightens or loosens the belt. So the variable speed is only achieved by letting the belt slip on the pulleys.
How does variable speed work on other brands of front wheel drive mowers?