Hot Ticket

The entertainments industry is in a state of flux. The EU has announced that from 2020 stage lights in their current form will no longer be permitted. Stage lighting uses arc lights and high-energy tungsten bulbs. Until now theatrical performances have received an exemption from rules enforcing the use of low-energy bulbs, but the Commission’s latest round of legislation has removed that exemption. Unfortunately no replacement is available. Technology does not as yet exist for low-energy versions of the type of specialist lighting rigs used in theatres and show venues.

Yet if live theatre is to compete with film and television, it has to produce visual spectacles and special effects to complement the performance of the actors and musicians on stage. Hollywood’s increasing use of computer-generated effects has upped the ante for stage set designers. So special effects for stage shows, music arenas and even sporting events—remember the London Olympics?—have become ever more spectacular and the equipment that provides them has similarly become more specialised and sophisticated. This includes the machinery for lifting and moving that equipment around.

“Not that many years ago, stage scenery was fairly static, being moved only during the interval when the curtains were closed,” recalls Tony Ingham of Sensor Technology, who are helping to introduce safety systems and automation to the theatre industry. “Then the big theatres in the West End and on Broadway started to emulate some of the things you see in the movies. Looking back, those early efforts were pretty crude, but you would say the same about long-running film franchises such as James Bond or Indiana Jones.”

“Many stage props and almost all of the backdrops are lowered onto the stage from the fly tower just behind it. Usually this is done quickly between scenes, but sometimes it is during—and as part of—the actual performance. Either way, safety and reliability are essential.

“Until recently, the sets were manually controlled with a technical stage manager watching everything from the wings and giving instructions by radio to the winch operators above,” says Ingham. “Speed is of the essence during scene changes, but you have to be confident the winches won’t fail.”

The hoists used for lifting scenery, lighting rigs and sound systems are therefore no longer general-purpose. Indeed several hoist manufacturers have separate divisions and products aimed solely at supplying the entertainments industry.

CM-ET, the entertainments division of Columbus McKinnon, supplies lifting equipment to international sporting events and for musicals and theatres from Broadway to the West End, and Las Vegas to Sydney. “It is an exciting time to be a part of entertainment industry,” says Nick Fleming, their business development specialist for entertainment. “The advance of technology over the past decade has really pushed us to keep innovating our product line to ensure we can continue to support what the new technology demands.”

Typical design criteria for such hoists are precision in operation, unobtrusiveness—so as not to distract from the spectacle on offer—and quiet running. Compact designs for setting up in smaller venues with limited headroom are also in demand.

CM-ET’s Prostar range is designed for small venues. Their Lodestar range, for lifting and securing overhead truss systems, lighting arrays and speaker clusters, was introduced as far back as 1955. Developments and improvements continue. Variable speed is now part of the latest offering in the range.

“In the past year we have followed up our launch of the Prostar VS with the recent launch of the Lodestar VS to offer variable speed when precision load control is critical at higher capacities,” says Fleming.

In industry and construction, people walking underneath suspended loads is a no-go. In theatres and venues, it happens— not merely because actors are not always entirely focussed on the rules of ordinary life but because the general public are there as well. Regulations are strict—we shall enlarge on them shortly—but the Lodestar D8+ has a 10:1 design factor that allows it to be used for suspending loads above people without a secondary support. It is equipped with double brakes and a clutch outside the load path acts as an overload device.

Unobtrusiveness can be achieved in simple but imaginative ways. To that end CM-ET listened to customers and are now supplying a chain coated in black phosphate. “This past year we answered the request for a chain that is less reflective and will blend in better in an entertainment setting than our standard chain offerings,” says Fleming. “Our brand new Black Phosphate Chain gives the exact same strength and safety properties as our standard chain, but with a black finish that will blend into the background and stay out of sight of the audience.”

They are not the only manufacturers to adopt that simple but pleasing solution. Swiss manufacturers GIS have recently launched and extended their LP electric chain hoist series for the entertainments industry.

“The chain hoist is a workhorse of the entertainment industry,” says Alison Marshall of Lift Turn Move (LTM), Bromborough-based partners of GIS. “This system brings with it design to the latest available standard, with a light weight, specialised chain for extra capacity, and IP65 as standard. This provides a solution for a variety of entertainment applications.”

The LP500 was the first of the range, introduced at the start of 2017. It has a low dead weight, at 12kg for 320kg lifting capacity; quiet running at 65 db; and speeds of up to 32m/min. The series offers a 60% increase in lifting capacity with one chain fall (D8 hoist) over its predecessor model, alongside a substantially increased life cycle. The LP1000, more recently launched, has a lifting capacity of 1.6t. Quiet operation, as we have said, is a necessary feature of stage hoists.

The LP series achieve it, says GIS, by self-contained helical-cut, three-stage gearing with permanent lubrication. The motor features grease lubrication—oil spots from hoist motors are not wanted on-stage—and there is a proven DC spring-loaded brake and dry-running slipping clutch. Case-hardened and manganese-phosphated—that is, black and non-reflective—profile steel chain offers an increased lifting capacity of 15% over conventional round steel chain with the same nominal diameter.

“The hoists are designed to meet D8+ specifications, for static suspension without secondary safety, which is the most common requirement now for rigging suspensions across the UK and Europe,” says LTM. “The whole design process of the hoist was to enable the use of this hoist in this specialised environment, whilst still making it practical to use and operate.

“This was required due to the latest standards. Most hoists across companies were de-rated to meet the D8+ standard, whereas this hoist range has been designed with this specifically in mind.”

New European regulations are being written, say LTM, and the UK expertise is a big part of the development for this. “Until this is completed then D8+ is the generally accepted standard for static rigging requirements. For example if you want to tour in Germany you would have difficulty using the older standard hoists that were used in the past.”

Regulations require high integrity hoists prepared for incorporation into D8+ hoisting systems to be enabled to hold loads at rest above people without using a secondary safety component. LP D8+ entertainment hoists allow load holding above people when loads are static, although staging processes that involve movement are not allowed with people below the load. D8+ requirements also include a second brake, and lifting capacity to give an increased safety factor of at least 8:1 according to DIN56950-1, 2012. On the LP series the clutch overload device is mounted outside the drive train, so that in the event of clutch problems, the load is not compromised.

“Raising and lowering systems are commonly used within the entertainment industry to make high level equipment like lighting or speakers easier and safer to access for maintenance and adjustment,” says Ed Penny, general manager of Penny Hydraulics. “It is common for people to move directly below these suspended loads and as such, hoists that do not conform to BS 7905-1:2001 require a secondary means of supporting the load when at high level (BS 7906-1:2005).”

The general upscaling of skills and a greater understanding of legislation and standards within the industry has seen Penny being called in to thoroughly examine many old hoist systems in recent years.

“The trend we have noticed is that many of the hoists we examine that do not conform to BS 7905-1:2001 fail the examination due to a lack of a secondary means of support for the suspended load at high level,” says Penny. “The latest Contact Suspension Unit design iterations and our new direct acting brake design on our multi wire rope hoists are in response to this increased demand.”

The Penny Hydraulics Group currently has research projects running in partnership with Derby University. One of these is looking at a mobile test rig for dynamically load-testing chain blocks used in the theatre rigging industry. This will reduce the need to carry test weights and greatly speed up the testing process.

As well as the LP hoist developed with their Swiss partner GIS, LTM have redesigned and upgraded their Guardian Controller range. This controls a variety of electrical hoisting equipment including chain hoists and winches. The panels can be customised to include touch-screen operation, variable speed panels or other types of stage machinery. It is, says LTM, easy to install and simple to operate and was designed by entertainment industry experts with many years of experience in the demands of the theatre engineering world.

That experience suggested a robust case to withstand de-rigging and transport between venues, and an option for a remote operating station, enabling the user to safety use it from wherever is most appropriate for the particular performance.

“There seemed to be a gap in the market for a simplistic but robust controller system such as the Guardian design,” says Marshall.

“The inspiration was the need to provide a great value but high quality control solution to address that gap.”

It has been used on multiple projects since the upgrade has taken place. And LTM is finding that business is booming: “The market for entertainment has increased dramatically this year. We have noticed a substantial increase in business from staging companies for our larger capacity hoists. And there has been an increase by staging and production companies for several high profile world tours. The skills and experience of the people involved are driving the demand.”

Tony Ingham’s Sensor Technology of Banbury is similarly improving safety control mechanisms for theatrical events. Their system uses real-time load signals from the winches. The data is monitored by a computer in the control room so that instant action can be taken if any loads move out of tolerance.

“We developed the load cells, which we have called LoadSense, a couple of years ago, originally for monitoring cargo nets carried under helicopters,” says Ingham. “We were asked to develop robust, industrial-grade wireless communications within the cell and were delighted to do so because we could see that the technology would transfer to many other fields— although I didn’t realise it would get to be a backstage pass to a world of greasepaint and legwarmers!

“In basic terms, each LoadSense has an on-board radio frequency transmitter which sends signals to the control room computer. The transmitter has to be physically robust to cope with the environment it finds itself in and capable of maintaining its signal integrity through the most corrupting of harmonic conditions.

“By working in real time, we can act instantly to any problems. For instance, if a load starts running too fast we would slow it down immediately. If a prop is heavier than expected this could suggest someone was standing on it so shouldn’t be whizzed 50 feet into the air at high speed. In fact, in this case, the computer ‘jiggles’ the load for a second or two as a warning to encourage the person to step away. If the load then returns to normal we are happy to let it rise; if it doesn’t, the floor manager is alerted by an alarm to check the situation.”

LoadSense is proving so sensitive that it can provide a feedback signal to close the control loop on a vector drive controlling the winch. Normally theatre engineers use sensorless vector drives, which offer good dynamic performance without the complications of wiring in a feedback sensor.

“In fact, theatre engineers probably work in more demanding conditions than manufacturing engineers,” says Ingham. “Everything has to be right on the night, harmonic corruption is at stratospheric levels, there can be major changes at a moments notice, people run through the ‘machinery’ without a thought for personal safety.

“But with automation some order is brought to this creative chaos. In fact, the health and safety inspectors now insist on it, with lots of failsafes and feedbacks. I honestly don’t think theatre engineers would be able to achieve half of what they do without wireless communications.

There would be just too many wires running all over the place and inevitably some would get broken at the most inopportune of moments.”

The entertainment industry encompasses more than theatres.

Penny Hydraulics designs winches for chandeliers and heavy lighting setups in residential buildings so that they can be lowered for cleaning and maintenance.

“So the criteria we work towards for those work well for such things as lighting rigs in the entertainments industry,“ says Ed Penny. “Typically they are quiet; they have secondary support mechanisms for safety; and we have a contact suspension make and break unit which gives a mechanical lock in the raised position and relieves the winch, pulleys and wire rope from tension.

Unlocking the unit to lower the load automatically breaks electrical circuits, which means that no live cables are lowered with the fitting.” The contact suspension units can accommodate loads from 5-560kg with a maximum of nine electrical contacts plus earth.

“We have just finalised the development of a direct acting hoist drum brake, an added safety feature which will be implemented on all new multi wire rope hoist systems. The brake has been added to supplement the other safety features of our multi wire rope hoist systems and is designed to arrest a load should there be a catastrophic failure of the interface between the gearbox and hoist drum. This new mechanical brake design engages whenever the hoist drum is stationary, ensuring the drum remains locked at whatever level the load is stopped at during the raising or lowering process.”