Soft Start / Soft Stop

Soft start / soft stop is a motor control feature built into DC-powered garage door openers. When the opener receives a command to move, the motor does not go straight to full speed. It ramps up gradually. As the door approaches the open or closed endpoint, the motor slows down smoothly before stopping. This is the opposite of an older AC motor opener, which starts at full power and stops abruptly.

The technology was developed to reduce wear on openers and doors. A sudden full-speed start puts a jolt through every moving part: the drive chain or belt, the trolley, the J-arm, the top section of the door, and the roller-hinge joints. Multiply that jolt by 10,000 cycles and the accumulated stress is measurable.

Key benefits:

• Less noise. The gradual start and stop remove the clunk and bang that older openers produce. This matters in homes with living spaces above the garage.
• Longer equipment life. Reduced shock loading extends the life of belts, gears, and door hinges.
• Better for heavy doors. On larger or heavier doors, a controlled start prevents the door from swaying or racking when it begins to move.

Soft start / soft stop is standard on most DC-motor openers sold today. It is enabled by the same DC motor that allows battery backup. AC motors cannot ramp speed this way because the supply frequency controls their speed.

For example, a LiftMaster 8500 jackshaft opener with soft start / soft stop opens a 16-foot wide door without the rumble and thump that chain-drive AC openers produce. Neighbors in attached townhomes often notice the difference immediately.

The limit switch or encoder tells the opener where the endpoints are. The soft-stop logic decelerates the motor in the last few inches of travel before the limit is reached.