Cirque du Soleil, based in Montreal, Canada, has earned a reputation worldwide for captivating audiences with creative live productions, combining acrobatics, athleticism, and live music. While talented performers may be the most visible stars of Cirque du Soleil’s several different themed shows, behind the scenes a team of dedicated people, coupled with sophisticated technology, make an indispensable contribution to the performance.
One of Cirque du Soleil’s most popular shows is “O”, which premiered in 1998 at the Bellagio Hotel and Casino in Las Vegas, NV. “O”, a water themed production, has a unique stage with four sections that move independently. In under a minute, the stage can be switched from a dry stage to a pool to incorporate synchronized swimming, diving from heights of up to 60 feet, and a variety of floating props into the production. The floor has many small holes to allow the water to drain quickly as the stage moves up and down.
The stage’s four sections are raised and lowered with three hydraulic cylinders each. Each hydraulic cylinder is equipped with a linear position sensor and is controlled by a proportional directional control valve. When the valves shift to supply hydraulic fluid from the pump, hydraulic cylinders raise the stage. When the valves are shifted to allow fluid to exit the hydraulic cylinders, gravity causes the stage to lower. When the valve closes, it holds the fluid inside the hydraulic cylinders, keeping the stage in place. The electronic controls system reads the signals from the linear position sensors and modulate the output to the proportional valves to keeping the stages level. Cirque du Soleil wanted to improve the stage’s performance. The main goals were smooth operation and decreased maintenance costs.
With the original hydraulic cylinders, the movement was often jerky. The hydraulic cylinders used a tubular jacket that moved with the rod and provided an air filled buffer between the hydraulic cylinder rod and the water. Over time it became possible for water to enter this buffer, making it necessary to blow compressed air into a port on the tube forcing water to flow out of a second port. If this was not done, the water in the buffer could negatively affect performance, as well as enter the cylinder and contaminate the hydraulic fluid. Completing this process for each hydraulic cylinder was time consuming. It also required grease, a contaminate to the clear pool water, to be packed into the head on a regular basis. The outside of the tube corroded over time, contributing to the friction, damaging the seals, and allowed more water to ingress the buffer making smooth operation difficult.
SunSource, a leader in industrial and mobile fluid power distribution based in Bloomingdale, IL, gathered the initial requirements and partnered with Aggressive Hydraulics®, a manufacturer of purpose built hydraulic cylinders based in Cedar, MN. Aggressive Hydraulics designed and built the first set of replacement hydraulic cylinders for “O”, which were installed on the first of the four stages in December of 2016.
Although operational improvements were desired, it was necessary to keep other aspects of the hydraulic cylinders the same, including; stroke, retracted length, mounting, and speed. Typically, sensors are inserted in the base end of the hydraulic cylinder and the probe fits inside the rod. For “O”, the sensor is mounted in the opposite direction of the hydraulic cylinder, allowing it to be removed or installed with the hydraulic cylinder mounted in place. The “O” team created a special water resistant enclosure for the portion of the sensor where the sensitive electronics and connectors are located.
Because the entire hydraulic cylinder is exposed to the pool water, specific materials and coatings were selected to prevent corrosion. 316 series stainless steel was selected for the guide rod and housing for the sensor probe. For the main barrel and rod, it was necessary to use carbon steel to meet the size and strength requirements. Underneath the chrome plating, the rod was first plated with a layer of nickel to create a barrier to protect the carbon steel rod material. The main barrel was sandblasted and painted with a two part epoxy paint specifically for wet environments. Leaded tin bronze was selected for the head gland.
Instead of the external tube to provide an air buffer, based on previous experience, Aggressive Hydraulics used seals to keep the hydraulic fluid inside the hydraulic cylinder and keep the pool water out. Aggressive engineers designed a head gland arrangement that included a primary and secondary rod seal, wear bearing, bidirectional seal, and rod wiper. The bidirectional seal is capable of sealing against the low pressure of the water, as well as keeping any hydraulic fluid that leaks past the primary and secondary rod seal from entering the pool. An additional port located between these seals provides immediate indication of a leak from either side. For maintenance, the head gland can be removed, resealed, and replaced with the hydraulic cylinder in position because the design does not use any seals on the piston.
The result of this collaborative effort is replacement hydraulic cylinders that “drop in” and meet the improvement goals. Operation is smooth during both the raise and lower cycles. The time consuming tasks of purging the air and greasing the head is no longer required. The weight of each new hydraulic cylinder is about half the weight of the original, making handling and installation much easier.
Purpose built hydraulic cylinders aren’t just for Cirque du Soleil. If you have an application you’d like to see better performance and longevity in, contact our hydraulic cylinder experts at 866-406-4100 and we’ll work with your team to create a purpose built solution.