MUSEUMS SOMETIMES need to move large, heavy, and awkward objects, which might mean anything from taxidermy mounts to stagecoaches, unbalanced sculptures to huge paintings to aircraft, and many crates. In any moving or rigging task, safety is the most important consideration. Although the object being moved may be very valuable, there is nothing more valuable than human health and safety. The tragic death of artist Luis Jimenez in a rigging accident in 2006 reinforces the potentially deadly nature of some of these operations.1
Humans are all equipped with intuition; the gut feeling about things that defies explanation but should never be ignored. If something does not seem right, it probably is not. The careful move planner will trust that intuitive feeling and call an immediate halt to any moving project that does not feel comfortable or inspire confidence.
The number-one rule in moving is to leave an escape route open. It is one thing to steady a crate as it is being lifted or moved, but something else entirely to try to keep one from tipping over once it has started to fall. Always allow room to get out of the way immediately if things go wrong, and never allow any body part to be trapped between an object that is being lifted or is unexpectedly falling and an immovable surface.
Personal protective equipment (PPE) should be used when lifting and moving objects. PPE includes good quality gloves to protect hands from splinters and sharp edges, steel toe boots, a back brace when lifting heavy objects, and safety glasses when appropriate. All personnel in the vicinity of overhead lifting should wear hard hats.
Rigging enables the lifting of a heavy object (such as a sculpture, a piece of equipment, or a large artifact). Outdoors, rigging usually involves a truck-mounted crane; indoors, a forklift, chain hoist, or block and tackle may be used. The hoist may be attached to an A-frame gantry or to a structural element of the building.
Although rigging is a special skill that requires training and experience beyond the experience of most registrars and collections managers, it is important to understand the concepts and terminology involved so that you will know when to call in the experts and be able to tell that contractors know what they are doing; when working in a remote location where only one local crane company is available, you must be able to evaluate whether the personnel can handle the job satisfactorily.
The first step is to determine the weight of the object to be moved. This information may be readily available from a shipping document, a label on the object, catalog information, or design drawings. More often than not, the weight will be unknown and must be estimated by calculating cubic footage and consulting a chart (see TABLE 5M.1) that gives the weights of various materials per cubic foot.
Based on the weight of the object, select equipment that is sized to lift the object within the appropriate safety margin. A crane or other lifting engine should be located as close as possible to the load because lifting capacities decrease dramatically with distance. A professional rigger will use a chart that calculates the capacity of the crane based on distance and boom angle to properly size the crane.
Safety margins are typically three-to-one, which means that the capacity of the lifting engine and the capacity of the slings, chains, cables, and hardware are rated at three times the actual weight of the object. Such a large safety margin is necessary because the capacity of a crane is calculated when a load is close to the body of the crane and the boom is retracted, but this capacity decreases with the distance a boom is extended and the angle that it is lowered. It is easy to make an error when calculating the actual weight of the object or the capacity of the crane with the boom extended and lowered. Although the hardware should be regularly inspected, it is possible the hardware may be overstressed or substandard and, thus, below its rated capacity. The operator might be less than smooth with the lift, putting an additional strain on the equipment and hardware; it is better to be safe than sorry.
Table 5M.1 Weights of Common Materials in Pounds per Cubic Foot
| Category | Substance | Weight in Pounds |
| Liquids | Alcohol | 49 |
| Gasoline | 42 | |
| Oil | 58 | |
| Water | 62 | |
| Masonry | Brick | 128 |
| Concrete | 144 | |
| Concrete (reinforced) | 150 | |
| Marble | 169 | |
| Stone | 158 | |
| Metals | Aluminum | 165 |
| Brass | 535 | |
| Copper | 560 | |
| Iron | 480 | |
| Lead | 710 | |
| Steel | 490 | |
| Miscellaneous | Clay | 120 |
| Loose Earth | 94 | |
| Glass | 160 | |
| Ice | 58 | |
| Mud | 102 | |
| Wet Sand | 128 | |
| Tar | 75 | |
| Wood | Oak | 54 |
| Pine | 34 | |
| Walnut | 41 |
The key to a safe lift is rigging to lift directly above the center of gravity. If the center of gravity is off to one side, the load will swing dangerously to the center when it is lifted. Any load swing of more than five degrees requires that the load be lowered and rerigged. The center of gravity of the object should be below the pick points or lifting points; otherwise, the load will flip when lifted.
Loads are often lifted with slings. Sling selection will be based on the size and type of load. There are three basic types of slings: chains, wire rope, and synthetic webbing. In most museum settings, synthetic web slings are used because chain and wire rope slings may damage the surfaces of objects.
Alloy steel chain slings are strong but must be carefully inspected prior to each use because the individual links can become stretched, as evidenced by an inward bend in the oval of each link. Attached hooks should be inspected for cracks, twists, or excessive wear on the bearing surfaces. Chains and hooks should be free of gouges or nicks; any of these defects are cause to remove a chain sling from further service.
Wire rope slings are composed of individual wires twisted together to form strands. Wire rope slings must be visually inspected prior to use. Slings should be rejected if they have an excessive number of broken strands, show severe corrosion, show localized wear, kinks, bird caging (a strand that has become unwrapped and bulged outward), or damage to the end fittings.
Synthetic web slings are commonly made of nylon, polypropylene, or polyester. The advantages of this type of sling are its strength, load protection (webbing grips the load without marring the surface), and shock absorbency. Slings should be rejected if they have burned or melted surfaces, snags, tears, cuts, or broken stitches. Some manufacturers build in a red indicator layer below the surface of the webbing. This way, as the upper layer is stressed and torn, this red layer will show through (reject any sling showing red indicator fibers).
Sling angle is important. If two or more slings are attached to a central point, a sling angle less than forty-five degrees will place a great stress on the slings and hardware, reduce the rated capacity, and can be dangerous.
Occasionally a spreader beam is used as part of the sling setup. A spreader beam effectively distributes the load across the beam so it must be sized properly and its weight included in the weight of the load calculations.
Hitches are used with slings to attach the hoisting engine hook to the sling and to attach the sling to the load. An experienced rigger will know which hitch is appropriate to use for the job, based on the load. Sling hitches include single vertical hitches, bridle hitches, single-and double-basket hitches, double-wrap basket hitches, and single-and double-choker hitches.
Most moving projects involving crates or exhibition furniture depend on human power as the lifting engine. These moves occur frequently in a museum and require appropriate procedures and equipment to be done safely and efficiently (see CHAPTER 5B, “Object Handling”).
Most traveling exhibits are housed in crates that arrive by truck, which means that the crates must be unloaded and moved to an unpacking area, then re-packed and reloaded when the exhibit closes. Many museums store part of their collections off-site and regularly move objects from storage to the museum and back again. The tools most commonly used for these moves include four-wheel dollies (commonly known as furniture dollies or piano moving dollies) and two pieces of leverage equipment, two-wheeled hand trucks and J-bars.
Furniture dollies consist of two hardwood crossbars equipped with swivel, ball-bearing casters mounted on each end. Above these wheels and perpendicular to the crossbars are two padded bumpers attached on each end. The crossbars may be covered with rubber or carpet pads.
A good quality dolly is well worth the expense. Most dollies have a capacity of 800 to 1,200 pounds. A local moving company will know the source of such equipment and may be able to order them at a wholesale price. Large casters with soft rubber wheels are the best. The more uneven the surface to be traversed, the more important are larger diameter casters and softer wheels to reduce vibration and make the dolly easy to move. Small casters with hard plastic or rubber wheels will give satisfactory results only on a very smooth surface.
Padded rubber surface bumpers minimize the shifting of the load when rolling over an uneven surface or transitioning across a threshold (the load tends to shift much more under these circumstances). Carpeted dollies are designed to protect fragile surfaces such as the finish on a piece of furniture. Unless the dolly is used only for furniture, it is a good idea to provide further protection by placing additional padding between the carpeted bumper and the furniture. In a busy museum, furniture dollies are often used for crates and other objects, which may leave dirt and grit embedded in the carpet.
As a general rule of thumb, a healthy, strong human can lift no more than about one hundred pounds, but this must be done properly. Lifting should be done with the legs while keeping the back straight. Back injuries can occur when lifting as little as twenty-five pounds, if not done properly. A demonstration of correct techniques for lifting should be part of training in object handling.
The proper way to move a crate is to tip it up on one end, center a dolly underneath it, and then lower the crate onto the dolly. For light to medium crates, this is normally done with one or two people lifting one end of the crate. If the crate is heavy, leverage can be used. For example, using a two-wheel hand truck underneath the edge of the crate adds mechanical advantage to lifting. Pull back on the handle to lift the edge of the crate off the ground, but never apply more force on the handle than one person can muster to avoid overloading the capacity of the equipment. The handle of the hand truck can be pulled as far down as the floor if necessary to allow a dolly to be slipped underneath the crate. The bumper of the dolly should be placed as far back as necessary to center the dolly, with bumpers perpendicular to the crate. The dolly should be held up under the load (at an angle, with hands underneath the cross-bars) as the load is lowered down onto the dolly.
If the crate is too heavy to be lifted by one person using a hand truck, a J-bar (also called a Johnson bar or a lever dolly) may be used instead. A J-bar has a long (ca. five-foot) hardwood handle that is attached to a steel plate with a slight upward bend to it. Steel wheels are attached to each side of the steel plate. The leverage principle is the same as with a hand truck, but the J-bar has a much greater lifting capacity. If the lift does not raise the crate high enough for a dolly to be inserted beneath it, then 2 × 4 chocks (blocks of wood) can be placed under the crate, the crate lowered onto the chocks, and the J-bar inserted farther up under the crate to lift it higher.
Communication is key to the safety of moving operations. The person handling the hand truck should call out to the helpers, “Going up!” (or something similar) when lifting the crate. The person placing the dolly should wait until all upward movement has stopped before inserting it beneath the crate, then respond with “Come on down!” (or something similar) to signal the lifter to begin lowering the load. The lifter should reply “Coming down” before lowering the load.
Maneuvering crates through doorways and other openings requires particular care. Always plan an escape route in case the crate is inclined to tip (the taller the crate or piece of furniture, the more inclined to tip it will be). Steady the crate, but do not try to stop it from falling if it is on its way down. An escape route is needed for hands and fingers as well because they can be crushed by a heavy crate bumping into a doorjamb if hands are wrapped around the edge of the crate. Move carefully and deliberately to avoid these mishaps.
When the place to unload the crate from the dolly is reached, exercise the same care and attention as in lifting and placing the dolly. Be particularly vigilant about the location of feet to avoid crushing a foot or toes under a heavy crate as it is lowered to the floor. Communicate at all times to remain safe. Exhibition furniture should be moved in much the same way as crates. Common sense requires that objects be removed from exhibit cases or pedestals before they are moved.
Ideally, exhibit pedestals and portable walls should be constructed so that the cross braces that span the bottom just above the toe kick are spaced so that the bumpers of the furniture dolly fit just to the outside of the braces, allowing the dolly to be solidly locked in under the pedestal or wall when rolling it into position.
Anyone who is a reasonably good driver can learn how to operate a forklift safely. Someone who is familiar with forklift operation should train other users in its safe operation. A good final exam is for the new operator to unstack and restack a pile of six pallets one at a time without spilling a cup of coffee sitting on the top pallet.
Unlike a car, a forklift steers from the back wheel, requiring considerable operating familiarization—a slight move of the steering wheel will produce a rather abrupt turn. This feature enables the forklift to turn in very tight and confined spaces, but also creates a tendency to wobble back and forth when traveling long distances. For this reason, and because the load may obscure the view forward, some operators choose to travel in reverse (looking over their shoulders) if moving an extended distance.
The first step in lifting something with a forklift is to adjust the width of the forks. Most forklifts have adjustable forks that slide back and forth to accommodate lift points of various widths. The forks are heavy, however, and it often takes two people, one slightly lifting the fork at the far end and the other pushing on the back end, to slide them into position.
Forklifts have two adjustments to the forks that are controlled by the operator—raising and lowering the forks, and tilting the forks forward and back. After manually adjusting the width, the next step is to lower the forks to just above ground level and tilt them forward until they are level. Drive forward slowly until the forks are under the load and the load is as close to the back of the forks as possible. The next step is to raise the forks to lift the load, making sure that the load is stable. The forks should then be tilted back slightly to ensure that the load will not slide off the end of the forks.
Never allow anyone to ride on the forks or to have their hands anywhere near the frame that the forks attach to when raising or lowering the forks. Drive to the destination slowly and carefully, with the load riding as low as possible. On reaching the destination, slowly straighten the forks to a level position, lower them to set down the load, and back out slowly. It helps to have a spotter who can tell the operator when the forks have reached a level position because the operator’s view may be obstructed by the load or the front of the fork frame.
A forklift can be used in conjunction with nylon slings to lift an object from the top. In this case, the forks are pushed together and one loop of the sling is placed over both forks and pushed as far back on the forks as possible to prevent the loop from sliding off the front of the forks and to provide lift directly over the center of the object. This is most often done in an outdoor setting because the frame of the forks is usually too tall to clear the ceiling inside of a building. Beware of this height problem if attempting this type of lift inside a building.
When the driver leaves the seat of the forklift, the forks should be leveled and lowered to the ground. This precaution insures that no one will trip over the elevated forks and acts as an added emergency brake.
A pallet jack is essentially a small, human-powered forklift. It differs in that the forks are fixed (not adjustable for width), lift only about six to eight inches off the ground, are raised by pumping the handle, and are lowered with a lever that releases hydraulic pressure. Pallet jacks are used mostly for moving pallets around indoors but are occasionally useful for moving heavy objects that are not on a pallet. A pallet jack is often carried in the back of a truck to enable the driver to roll a pallet to the back edge of the truck where it can then be lifted out of the truck with a forklift.
Pallet jacks have small diameter steel rollers that pivot down from the fork that contains them, thus raising the forks. Occasionally a pallet will be constructed with a cross-piece of wood attached under the pallet in a direct line with the wheels of the pallet jack. In this situation, raising the forks forces the pallet apart rather than raising it off the ground. The solution is to back out the pallet jack slightly until an open space is found for the wheels.
On rare occasions there may be a need to pull a load a short distance to gain access for a piece of equipment to do the lifting. For example, a heavy crate that is to ward the front of a truck may have to be pulled toward the back before a dolly can be placed under it. This is commonly done with a chain or cable wrapped around the crate and pulled with a forklift. This can be a dangerous operation and requires extraordinary caution. If a cable breaks, it can recoil with such force as to cause grave bodily injury or death. The most likely path of recoil is directly back toward the source of the pulling power, but a cable can whip out to the side as well.
A cable is much more likely to recoil than a chain, so the best choice for pulling is a chain. The chain should be attached as low to the ground as possible. All personnel should be away from the path of the chain (at least 1.5 times the length of the chain). As an added precaution, a packing blanket should be draped over the chain while pulling. This will absorb some of the energy in any recoil, should it occur.
Inevitably, everything in the museum will move at least once (and probably more than once), so why not design things in a convenient way to move them? In the past, this was part of the design process. Large industrial artifacts, even old ones, were usually designed with moving pick points in mind. Large engines and motors almost always have lifting eyes and loops attached at convenient places. A thoughtful sculptor might design an element of the piece that can be removed and temporarily replaced with a lifting eye for lifting and moving, or a piece might be designed so that it can be moved with a forklift using slots at the base that accommodate the forks.
If given a choice, ask for all large incoming objects and equipment to be delivered on pallets. This will make the job of unloading and moving much easier.
Exhibition furniture should be designed so that it can be easily and efficiently moved. If the museum’s mission calls for collecting or exhibiting large objects and sculpture, buildings should be designed to accommodate the moving of these pieces. Doorway dimensions, elevator dimensions, and lift capacities should all be large enough to make moving tasks simple and routine.
Rigging and moving are necessary tasks that all museums undertake. Because these activities hold inherent danger to people and objects, using common sense and working safely are goals that all should strive for.
1. Available at: https://www.dailyartmagazine.com/death-art-untimely-death-luis-jimenez/ (accessed June 13, 2009).