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An independent festoon for the pendant allows the operator to stand anywhere along the length of the crane when operating, not just next to the hoist. The pendant cable runs on a second separate festoon track. This is important when rotating long items or if the operator must lift from a pit or truck or walk in a crowded area. Because of the reduced cost of remotes we are seeing more remotes in place of independent festoons.
Remotes are used in situations where being
tethered to the crane is inconvenient. In applications where the operator
must walk around an object to assure proper positioning, such as truck
repair facilities, remotes allow one operator to do the work of two
people.. In facilities that move long items the remote allows the operator
to balance the end of the load eliminating the need for an extra person.
With improved reliability, added safety features, and lower cost remotes are
an option we are seeing on increasing numbers of cranes.
Variable drives are typically added to all
but the lowest cost cranes. A variable drive improves efficiency and
safety. By allowing infinite speed control and ramping the speed up and
down the operator can move loads faster with no dangerous load swing. The
very slow speeds available allow accurate positioning where the faster
speeds allow moving cranes with no load or small loads quickly. A variable
drive bridge and trolley can save over 50% of the movement time over a
single or 2 speed crane. We typically do not recommend variable drives for
hoisting as the cost is much higher and the benefits are less.
In applications where cranes are used
continuously the owner should consider larger, hardened steel, wheels and
larger motors to extend the life of the crane. A 12 inch wheel turns half
as fast as a 6 inch wheel for the same crane speed. This greatly increases
the life of the bearings, gears, as well as wheel surface. A larger motor
puts forth less effort to move the crane and has more surface area for
cooling. This reduces the temperature of the motor increasing its life.
Time is money. Doubling the speed of a
hoist can reduce the load time by as much as half for as little as
$2000.00. Loading trucks you will typically lift about 5 foot (10 foot of
movement per cycle) . Doubling the speed from 16 to 32 FPM saves about 20
seconds per load. With as few as 50 lifts per day this option will pay for
itself within a year.
Typical single speed bridges travel at 60 or 70 FPM. Even with a short, 60 foot long, building it will take 1 minute to travel this distance. We strongly recommend higher speeds used with variable drives. The variable drive allows slow and fast motions along with ramped acceleration and deceleration. 140 FPM is a medium to medium slow walking pace and we have found is a safe and comfortable pace for a crane. Even if you find that it is faster than you want the variable drive allows the top speed to be reduced to as low as you wish.
Recommended for the same reasons as bridge speed.
Safety should always be a prime consideration when lifting and moving loads. A horn is used to warn others of approaching load. We have found that a horn activated by motion does not work well with cranes, especially when more than one crane is in a building. The constant beeping tends to be ignored over time. ACI uses a horn activated by a button on the pendant. This allows the operator to warn others when necessary without having the continuous beeping. We use a very loud, 110db at 1 meter, horn to assure the horn is heard over shop noise.
A strobe light is added for safety also. Unlike a horn that looses effectiveness if activated on motion the light is very effective on motion and does not require operator interface. A light also works well in very noisy environments.
When loads must be placed down softly a second speed is important. This allows the operator to lift at a faster speed saving time and place the load gently with the slower speed. Most hoists have a second speed that is 1/3 to 1/5 the high speed although some offer 1/10. We have found the 1/10 is to slow to be useful in most applications.
These are required on hoists used on crane systems (there are some exceptions to this rule but they are required in most applications) Some crane manufacturers assume that because many hoist manufacturers only offer this as an option that it is not required and do not include it.
Most electric chain hoists do not have a chain container as a standard item. You should verify it is included in your quote.
Many hoists are designed with a second mechanical load brake. This brake assists in the braking process and helps control the decent rate. Although a single brake system is safe many people like having a second brake as a added security.
Cranes are required to have a non-coasting mechanism on the bridge and trolley. This can be done with a worm gear or a brake. Many manufacturers do not include this even though is is a requirement.
Conductor bar for power along runways comes
standard with a single collector shoe for each phase. As system ages
conductor bar will get rust and other contaminates which will cause the
single collector shoe to loose contact in spots. This single phasing
damages motors and brakes and electrical equipment. In order to minimize
this dual collectors can be used. Unless there is a very long section of
bad bar the dual collectors assure power is not lost.
Although the National Electric Code presently allows the crane wheels to be used as the ground we recommend a 4th conductor bar be used. We have found in many instances, over time, the runway rail either gets painted or contaminated with dirt causing loss of ground.
When installing a hoist in an explosive environment class group and division must be specified. Explosion proof hoists are very expensive. Air hoists can be used as a less costly explosion proof alternative.
Spark resistant is completely different from
explosion proof. If you order an explosion proof hoist it will not come
with spark resistant hook, chain, or wheels unless you specify spark
resistant.
- Many crane builders have begun using SO cable or tray cable across the bridge instead of conduit. Although much less costly this DOES NOT meet National Electric Code requirements (610-11). Wiring, with the exception of festooning and very short pieces to the collectors, must be armored or in conduit. All ACI cranes use conduit. NOTE: Everyone will say their crane meets code. You should ask if they use conduit, but the best way to make certain is to specify that the wiring be in conduit. (It is confusing when you are getting two different stories. If you are not sure which is correct please ask our sales person. He will show you the code.)
- Although this seems like a good way to protect wires from being cut, and cuts the cost of a crane, we know of no cover that is UL approved or that meets National Electric Code. Wiring used in these covers is designed to be used in conduit and does not have the protective covering around it that a flat or SO cable have. Flat cable is specifically designed for festooning and is what ACI uses on all of its cranes.
- We have found the best way to increase the life of a relay is to assure continuous clean power. This can be done by electrical analysis to verify voltage drop throughout the entire system is not to high (ACI engineers verify voltage drop with each system we sell) and by using dual collectors to reduce the possibility of phase loss. We can offer higher amperage relays which will also increase the relay life is you wish.
- Cranes require branch fusing (one set of fuses for each direction). Circuit breakers can be used in the place of fuses although we do not recommend this. A crane blowing a fuse is a sign that there is a problem that needs to be fixed. Where circuit breakers are used we have found that people tend to reset the breaker, and if it holds do not find out why it blew. This is a safety issue, putting faulty equipment into service should never be done and it is extremely rare that a fuse will fail for no reason.
- There are many different styles of festooning. Everything from a stretched wire with metal rings sliding across to heavy duty trolleys designed to travel on steel beams. Except for very small job cranes we do not recommend stretched wire festooning. ACI uses a C track festooning and trolleys with roller bearings as a standard on its cranes. The C track system will work well for all but the heaviest or fastest use. ACI will offer upgraded festooning if we believe would be cost effective. If you wish more information please ask.
- There are several reasons to consider special conductor bars. Voltage drop – long runs and high current will cause low voltage to electrical components if proper conductor bar and wire is not used (ACI analyzes every system to assure this does not occur). Corrosion – Chemicals or high moisture can cause premature corrosion on conductor bar. In environments where this may occur we recommend a stainless or copper clad bar. Sun exposure. There are special UV covers for some conductor bars which may be considered. In many instances it the bar will need to be replaced due to corrosion at the about the same time the cover breaks down due to UV.
- In high dust or outside locations weather tight NEMA 4 electrical boxes and NEMA 4 wire grommets should be used.
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