2024 January 22

Read time : 10 m


What is an Elevator Overhead?

Overhead height, also known as clearance at the top, is one of the calculations that many elevator companies struggle with consistently, and its importance becomes evident when there’s also a limitation of space in the overhead area.

Overhead Calculation

Overhead refers to the distance from the floor at the highest stop to the underside of the elevator shaft’s ceiling. To calculate this dimension, we require an important prerequisite:

First, there is an air gap between the counterweight frame and the buffer, followed by the discussion of buffer compression. If the buffer is polyurethane, it compresses to 90% of the buffer’s height, and if the buffer is hydraulic, it compresses according to the stroke written on its plate.

Condition One

It is the additional length of the guide rail. After compression has occurred, the distance from the top of the shoe to the end of the rail must be 0.1+0.035v^2, which equates to 13.5 cm at speeds of 1m/s, 19 cm at speeds of 1.6m/s, and 24 cm at speeds of 2m/s.

Have you ever paid attention to what 0.035v^2 is?

This is the rebound. The counterweight frame may strike the buffer at speed and since the cabin tends to move upwards, it rebounds by 0.035v^2.

Condition Two

Refers to the free vertical distance between the highest point of the cabin’s ceiling and the underside of the elevator shaft’s ceiling. Here, we must know how much the standing space is. According to the standard, the standing space is 0.12m^2, with its smallest side not less than 0.25m. Hence, this nearly amounts to 25 by 48 cm. Now that we’ve determined the standing space on the cabin, we must have a distance of approximately 1m+0.035v^2 from the standing space to the underside of the shaft’s ceiling, which amounts to roughly 103.5 cm at speeds of 1m/s, 109 cm at speeds of 1.6m/s, and 114 cm at speeds of 2m/s.

Condition Three is about equipment

The distance of equipment means that the highest equipment we have on the cabin to the underside of the shaft’s ceiling must be 0.3m+0.035v^2.

The tall equipment that we have in our cabin can be a revision box or also it can be a railing. But usually, the highest equipment is the railing. We install the railing when the distance from our cabin to the wall is more than 30 cm. But be aware, that if this distance is less than 85 cm, we want a 70 cm railing, and if it is more, we need a 110 cm railing, after determining the height of the railing, we calculate 0.3m+0.035v^2 from the top of the railing to the underside of the ceiling.

The Fourth Condition

We must have a hypothetical cube with the dimensions of 50 by 60 by 80 cm on one of the faces on top of the cabin, which in 1:1 elevators can fit 15 cm inside the steel ropes.

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