Bailey's

It is a lever. The lifts are off center to the axle. Once the lifting handle is on the floor the fulcrum point is over center and keeps the handle down. It is simple but effective.

Oregon doesn't give a limit, but as long as its a ZTR, or Rotary mower, it will lift it.

This will hold the weight of the mower. As with any jack it is prudent to have a backup support in case someone where to run into the machine and throw it off the jack.