You have a wonderful day. Best wishes. Deas Plant.
Hi, John.
The earlier small gas tractors didn't have enough 'grunt' to need the extra grabbing power of an over-center clutch which does need a hand operated lever to actuate it. You can get a good bit more pressure on the friction plate with an over-center mechanism than you can with springs unless you have Magilla Gorilla standing by to depress the clutch pedal.
International Harvester brought out one iteration of their TD24 with a foot operated clutch - was NOT one of their 'more inspired' notions. But then the TD24 was not exactly an 'inspiring machine anyway.
Just my 0.02.