How do you assemble a tower crane?

Learn with LEGO Woman Series

Lego Woman in front of a crane

If you missed watching the set-up of West Park’s first crane, you’re in luck as two more cranes will be erected to help build the new six-floor hospital, basement and underground parking levels. 

You can watch the action tomorrow on June 9 when the second crane is assembled by the former main entrance or new south inpatient area. 

“Our next crane will be our tallest crane topping over 250 feet (about 24 storeys) high with a working arm of about 220 feet,” says LEGO Woman, West Park’s project manager for construction. “Manufactured by Terex, the crane is able to lift over 40,000 lbs or about 28 elephants!” 

West Park’s third and final crane will follow a few weeks later and positioned by the former Kingsley Fox Courtyard or future location of the new hospital’s outpatient area. Already operational, the first crane is situated in front of the Ruddy Building or the new north inpatient area.

For those keen on learning more about cranes, read on to learn how they are assembled, the parts of a crane and its purpose. 

Steps to assembling a crane

According to Wikipedia, the first known crane machine was the shadouf, a water-lifting device that was invented in ancient Mesopotamia (modern Iraq). Variations of the crane spread to ancient Egypt and Greece, and evolved throughout the centuries until the Industrial Revolution, which gave rise to the modern crane.

Below are the general steps to assembling a tower crane, a culmination of ingenuity throughout civilization.

Crane diagram

Learn the parts of a crane with the above photo of West Park’s first crane. Click on the image for a larger view

1. Creating the crane base 
About two weeks before assembly, construction workers create a solid foundation to support the crane. Weighing about 400,000 pounds, the crane base is typically 30 ft x 30 ft x 4 ft, and consists of a concrete pad with large bolts embedded deep inside to anchor the crane into the ground. 

2. Transporting pieces of the crane
Depending on the height, tower cranes arrive in pieces on 10-12 tractor-trailer rigs. Did you know it takes a crane to build a crane? A hydraulic mobile crane is also brought onsite to help lift the parts into the sky. 

3. Adding the mast 
Rising from the crane base, the “mast” or steel trussed sections are lifted by the mobile crane piece by piece, and connected by bolts until the desired height is reached.  

Mast of a crane

A mobile crane lifts and places a section of the mast, while construction workers secure it with bolts

4. Attaching the operator’s cab and slewing ring
Placed on top of the mast is the slewing assembly, which consists of two components: the operator’s cab on the top and the slewing ring on the bottom. The operator’s cab is the command centre of the crane. The crane operator controls all the crane’s movement with joystick controls, electronic monitoring devices and communications systems.

The slewing ring allows the crane to rotate with its gears and motor. According to tower crane company, Morrow, the slewing right is “fixed to a ball track and is made of several hundred precisely machined gear teeth” and is “capable of enormous torque, yet precise movement.”

5. Adding the tower top
Like a cherry on top of a sundae, the tower top is the tallest point of the crane. After the horizontal arms are in place (see below), pendant bars are attached from the tower top to the front jib and counterjib, which provide the crane with more stability and greater torque. 

6. Attaching the counterjib
Located behind the operator’s cab, the counterjib is the short horizontal arm that holds the crane’s gears, motors, electronics and concrete counterweights to prevent the crane from tipping forward when lifting a load.

7. Attaching the front jib
The front jib is the long working arm that is hoisted by the mobile crane either piece by piece, or all in one piece. A small team of workers, who are likely unafraid of heights, wait at the top and then secure the front jib in the air by pins. A trolley with a hook is then attached to the underside of the front jib to carry loads. 

Front jib of a crane
A construction crew works to secure the front jib

Until the next crane

A reminder that you can catch a glimpse of West Park’s second crane going up on June 9 via our construction cam at

It may look easy but installing cranes take a lot of coordination, precision and safety measures to get the job done. The next time you see a crane, we hope you have a greater appreciation for these structures. And feel free to show-off the new lingo you just learned!

About the Learn with LEGO Woman Series

Want to know more about what's happening on the construction site? The Learn with LEGO Woman (or man, when applicable) series will help explain the construction process throughout the build.

If you have an idea for a segment, please contact us at 416-243-3600 ext. 2111 or