Something Work related: Suspended Lift Pit

Here's something which usually as a mechanical engineer will definitely face during the design of shopping center or any other building for that matter. Say you have a small lift to serve a small number of floors, so you proceed to place that lift there with all the dimensions requirements. But sometimes you have a lift which does not serve all the floors, such as in a shopping complex, a small lift is placed at the center of the shopping center as part of the facade to serve the retail floors but not serve the basement car park below it. In this case you will definitely have a suspended lift pit since you do not want the whole lift shaft right through your car park as it will eat valuable car park space.

Below is 1 such lift, located at the new wing of IOI mall Puchong.


As you can see, it only serve only 4 floors and does not serve the basement below it. I can see it is a small capacity machine roomless lift since it appears there isn't any machine room at the top. This kind of lift is called a machine roomless lift, whereby all the motors and equipment are located in the shaft. This kind of lift is good for a short building as it does not need a huge room right at the top, but not advisable for tall buildings 12 storeys or more since if anything goes wrong, the poor repair guy have to be suspended up to 60-70 meters at the top of the shaft to get to the motor.

The close-up of the lift car.The counter-weight is at the side of the car. Some lifts have it behind the car, but in this case the counterweight will block the good view out of the lift. It is also why some lift have very long widths or depths to cater for the placement of the counterweight. The car operating panel for this lift is only located on 1 side of the lift car. Ok for a small lift, but if it is a big lift for a office building, it is better to have it on both sides.


To the visitors to this shopping mall, they will not notice all the finer details that went into the placement and installation of this lift. Even during the design stage, we as the mechanical engineer must coordinate with the architect and civil engineer on the placement of the lift so that is does not affect items like headroom, beams, columns, car park etc. It becomes important as we take a look at the lift pit from Basement 1, the floor below.


As you can see, the lift pit is something like a very big concrete box suspended from the ceiling. Lift pits vary in depth depending on the speed of the lift car. Some like in this case maybe 2m deep or less, while high speed lifts may have lift pits up to 4m deep to house the large buffer (something like a spring) to absorb the impact of the lift should the lift free-fall (very very unlikely, since it has a safety governor). But it can be a big issue when you have very little headroom to place the lift pit. As you can see, it is eating up 2 car park lots that might otherwise be available. But this is something like a compromise when you do the lift pit placement; you cannot have it in the driveway, you can't let the lift shaft run all the way down to lowest basement otherwise you would lose 4 car parks.

In a way part and parcel of being an architect is to watch out for stuff like this during the design stage. Sure on the Ground floor and above the placement of the lift is fantastic, but then it will obstruct the drive way or eat into some car parks or worse, fan rooms, electrical rooms, domestic water tanks etc. Always spot these stuff during the design stage because once the pit is casted and the mistake is realized, it will cost ALOT since a suspended lift pit must be able to withstand a lift free-falling onto it and not crack. No way you can hack this if such a mistake is done.

To the consultants and architects doing IOI mall, great work for coordinating this lift pit into a location where it will at most, eat only 2 car parks and not obstruct the driveway.

I'm just a frequent shopper to IOI mall, so this is my first time to the new wing since it was opened.