end of the lift platform has its own control valve, while all the rest of the handrail sections have one other control valve. Each handrail section has both upper and lower position switches, rated NEMA 4X. The air cylinders are supplied with soft-stop features, and the height of the handrails are the full stroke of the cylinders. When raised, the air cylinders are fully extended, and when lowered, they are fully retracted. The switches are there to report the position of the handrails, not to limit travel. At the lower landing, there is a wire-mesh enclosure that completely encases the pit, hoistway area, and a considerable area between the platform sill and lower landing gate. This area is required by the overhanging helicopter blades. A large double-swing wire-mesh gate is built into the enclosure at the loading end of the platform beyond the area required by the overhanging blades. To prevent operation of the lift if someone is standing here, category-4 industrial safety sensors are positioned to illuminate the location. All interlocks, switches and electrical devices are NEMA 4 or NEMA 4X rated. Control stations are located at the lower landing and at the floor below the upper work platform. In addition, there is a lift station with up/down buttons for the upper landing-sill handrail on the lift. The lift has up and down leveling switches, mid-level switches, and upper and lower limit switches. To combat the corrosive environment, all structural steel was been sandblasted and painted with ZRCÂŽ, Cold Galvanizing Compound, and the vertical sliding portions of the powered handrails were built of stainless-steel tubing.
Top to bottom: â&#x20AC;˘ Setting the cylinder â&#x20AC;˘ The platform, inverted, in Gillespieâ&#x20AC;&#x2122;s shop
Operation To operate the lift system, the lift is first called to the lower landing. The lower gate interlock is released by the car cam, and the gate is opened. The blade cart is then pushed onto the lift platform, and the gate is closed and latched. The lift can then be sent to the upper landing from the lower station or called to the upper landing from the upper station. The upper landing station has both lift control buttons, as well as handrail control buttons. If the handrails are not in their upper positions, they must be raised before the lift can be operated. After the lift has reached the upper landing, the landing-sill handrail is lowered, and the lift gates are swung out. The cart can then be moved onto the work platform to allow for the blades to be mounted onto the spin fixture. All the handrails will be up, and the work area will be secure. With the blades mounted to the spin fixture, the cart must then be moved back onto the lift, the gates closed and locked, and the landing handrail raised to its upper position. From the upper control station, the lift is then lowered to the midlevel landing, and the landing-sill handrail (in addition to the rest of the handrail sections) are lowered. With both the lift and handrails in a retracted position, the blades can be spin balanced. After completing the blade balancing, the handrails are raised to their upper positions, and the lift platform is called to the upper landing. The landing-sill handrail is lowered, the lift gates opened and the cart moved back onto the platform. With the blades on the cart and the cart back onto the lift, the lift gates are closed once again, the sill handrail raised and the lift sent to the lower landing. There, the lower gate interlock is released, allowing the gates to be opened and the cart unloaded from the lift platform. To prevent operation of the lift in an unsafe condition, all the handrails must be in their raised position, the lower landing gate closed and locked with the interlock and the sensor screen unblocked.
Conclusion Gillespie builds unique elevators, lifts and cranes. We undertake jobs that fall outside of the production lines of fellow companies in the industry. The helicopter-blade lift and powered retractable handrails presented unusual challenges. Once again, Gillespie feels it has demonstrated its ability to face a difficult challenge and arrive at a practical solution through imagination, engineering and manufacturing capability.â&#x20AC;&#x192;â&#x20AC;&#x201A; đ&#x;&#x152;? January 2015 â&#x20AC;˘ ELEVATOR WORLD