Eli5: Why is that when an elevator is about to go up, it first sinks a little bit?


Eli5: Why is that when an elevator is about to go up, it first sinks a little bit?

In: 62


This should be the brakes releasing on cable elevators.

At a stop the elevator engages basically a parking brake on the motor to keep it still without using power. The sinking is due to a the motor needing a slight bit of time to adjust it’s pull when the brake is released.

The same reason you might feel your car move ever so slightly when you release the parking brake (even if your foot is on the brake), especially if you’re not on flat ground. Because an elevator is hanging in the air (i.e. gravity is in full effect), you’re going to notice it more, but it’s just the elevator switching from one braking system to another.

So there are two types of elevators:

1. Overhead traction, basically a box hung from a steel cable with a counterweight.

2. Hydrolic driven, basically a box at the end of a large piston.

I would imagine this is either the valves on the cylinder cycling and pressure shifting or is a breaking system on the motor attached to the cables being a bit out of spec.

Source: Elevators are a special interest of mine… dont ask why.

Humans have developed as land animals. Our bodies inertial motion sensors are trash when it comes to vertical acceleration. With no visual reference the jerk of vertical acceleration is often felt as negative(falling.) This is why pilots use instruments in poor weather., and many passengers feel that same initial falling the first couple seconds after takeoff.