Mechanical Load Brake Operation and Inspection

There are many misconceptions of mechanical load brakes on lifting equipment. I have heard from many customers that they think the load brake is designed to hold the load during normal hoisting operation. This is not completely correct. I have also been told from customers that load brakes are required to be inspected on an annual inspection. This too is incorrect. There are two basic reasons hoist have load brakes. The mechanical load brake has to control the speeds when lowering the load, and has to be able to hold the load when the motor is not running. The load brake operates very similar to a nut and bolt. Let me introduce you to load brakes and give you a brief description of how the load brake works and see if I can help you understand the load brake functionality and inspection frequency for them.

During the hoisting mode the load brake is unlocked and freewheeling. The purpose of a “load brake in a hoist application is to keep the suspended load from falling without power to the hoist and independent of the motor brake.” When the load is being lowered the clutch locks stopping the load brake system from rotating. As soon as the motor stops driving the load, or the load travels faster than the motor then pressure will be applied to the friction disc. If the electric motor brake fails the load brake will completely lock to hold the load. You will also be able to lower the load to the ground. This is done by the self-adjusting clutch. The brake will tighten slowing the load, and the load brake loosens if it is going too slow. This is a rapid succession that keeps the load controlled. If you hear a clicking sound when the load is being raised, this is the pawl hitting the ratchet teeth. You should not be hearing this noise if the load brake is adjusted properly.

Let me explain my statement when I said that it is not completely true that the load brake is designed to hold the load during normal hoisting operation. The load brake actually works together with the hoisting brake. The Weston style load brake (pawl & ratchet) holds approximately 25 to 30% of the load being picked up. The holding brake does the bulk of the work. This is why it is vital to have your holding brake inspected frequently so the load brake does not end up doing all the work causing it to wear faster.

The other misconception is that the load brake requires an annual inspection. This is incorrect. All load brakes are self-adjusting and minimum maintenance is required. There is however cases the load brake require an inspection. If you hear clicking sounds coming from your load brake then an adjustment is required and can be done externally with the adjustment nut. However if it has been several years since the gear case has been opened and inspected than it is a good idea to open the gear case to inspect the brake linings and other components. Lubrication to the load brake is also highly important. Every time pressure is applied to the load brake the heat is dissipated by the lubricant. If not enough lubrication is in the gear case than the brake will over heat destroying the brake liners. In some cases forced cooling is required for heavy loads. The lubrication should either be changed out annually or lab tested. The viscosity of the lubricant is vital to control the operating temperature of the gear case. Old or dirty oil will change the original viscosity of the oil. Like anything oil too has a shelf life even if it is clean. If the viscosity or oil level is too high or too low it can cause overheating, excessive power consumption, and foaming. It is recommended to inspect the gear case and load brake every 4 years or per your OEM. Each OEM will have a different recommendation so check with your owner’s manual for inspection frequency. It is recommended as well to test the load brake annually at 25% of the load capacity. Not following your OEM recommendations could result to premature wear of your load brake.

I hope this small amount of information has been helpful to you. The inspection process although not annually is very important in safety of your crane and in extending the life of it. It may be a costly investment but it is vital in preserving the life of your crane and the safety of those that work under it.

How Much Can I Pick Up With My Crane?

As a certified crane operator instructor I have given many classes and I am always asked questions that become repetitive. I think those are the questions that need to be shared the most. Like, What is wrong with side pulling?, or Why do I have to inspect my crane so often? These are important questions and definitely should not go unanswered. There is one question that I get more than any other. I get this question in my training classes, I got it when I was a crane technician, and I get it as a consultant to my customers. How much can I pick up with my crane? Every time I am asked this I answer it the same way, You can lift whatever the lowest capacity rating you have on your crane system. Once I state this, I always get the counter question of, I thought there is a safety factor built into my crane? Well, yes there is but that don’t mean your crane was designed for lifting your rated capacity plus the safety factor percentage. In this post I will try to explain what the correct answer is, and then I will do my best to explain to you this safety factor.

The regulations set forth by OSHA clearly says that you are not to pick up more than the rated capacity of the crane. OSHA 1910.179 N states that The crane shall not be loaded beyond its rated load except for test purposes as provided in paragraph (k) of this section. Not only can you not exceed the rated capacity of the crane, but you also have to factor in the lowest rated capacity of the device your using to lift with. If you have a below the hook device you have to subtract the weight of the device from the rated capacity of the crane. Then if the rated capacity of the device is smaller than the rated capacity of the bridge or hoist then you cannot exceed the capacity of the device.

You should never pick more than the rated capacity unless it is for a load test which will be conducted at or near 125% of the rated load. So many factors go into the design of a crane that you would have to look at the safety factor of all your components. You would have to look at the wire rope, the motors, bearings, sheaves, drums, wheels, rails, hoisting speeds, and beam and steel sizes.

Now when you try to figure out what is your cranes safety factor, you have to be careful as to whether your crane manufacturer built the crane based on CMAA standards or FEM standards. So it is important to know what the difference is between the two standards. CMAA is the Crane Manufacturers Association of America and FEM is Federal European De La Manutention. This is the standards for design and manufacturing internationally of overhead traveling cranes. FEM specifications are written based on the input from the World’s largest crane companies. Then of the CMAA specifications are written based on the input from the largest American crane companies. FEM will separate each main part of the crane (hoist, trolley, and bridge). However CMAA groups them together as one structure and machinery. I think the problem you can have with this is that with FEM you can get an under and over designing of certain components because it does not always take into account the entire crane system as CMAA does. CMAA safety factor for the wire rope is 5:1 for standard cranes, and 8:1 for molted metal cranes. However, FEM safety factor for the wire rope of 3.6:1 and up to 9:1 depending on the crane group the crane is classified in. There are 6 classes of cranes for FEM and for CMAA. These different classifications were designed to allow for the most economical crane to be specified.

FEM         1Bm    1Am    2m    3m    4m    5m
CMAA      A        B         C      D      E      F
These classifications are based on the usage of the crane. They are similar to each other but different enough that it can put your cranes in different classifications.

FEM    Life in Hours
1Bm     0-1,600hrs
1Am    1,600-3,200hrs
2m       3,200-6,300hrs
3m       6,300-12,500hrs
4m       12,500-25,000hrs
5m       25,000-50,000hrs


CMAA   Life in Hours
A             0-1,250hrs
B             1,250-2,500hrs
C             2,500-5,000hrs
D             5,000-10,000hrs
E             10,000-20,000hrs
F             20,000-40,000hrs



Typically with the FEM standards you are getting a heavier duty hoist than with the CMAA standards. FEM also factors their calculations using the long ton while CMAA goes by the short ton. The difference is 220lbs per ton. This does not seem like a lot but when you are comparing a heavier capacity hoist it is a drastic difference. For example if your crane is a 30 ton hoist, CMAA standards will build the crane for 30 tons. Likewise that same hoist by FEM standards will be built for an additional 6,138lbs.

You also have to consider the deflection of your bridge beam when factoring in what your crane can pick up. When a load test is conducted on your crane deflections are measured. CMAA has an allowable deflection of live load tolerance. However FEM has no such rule. If we go by CMAA standards the standard allowable deflection is .1125% of the span of the bridge. A good rule to go by that I always used as a technician to find an acceptable tolerance is, Jib cranes tolerance is the span/150 or 450 depending upon the span. A single girder crane has an allowable tolerance of the span/603 and double girder cranes have a tolerance of the span/888. These tolerances are based on 100% of the rated capacity.

In the end the crane operator is the one who is responsible for the lift. It is the operator’s responsibility to know what the capacity of the crane and any lifting devices. If the operator has any doubts to the safety of the lift then they should not lift the load. Anytime that the lift is going to be at near capacity it is a good practice to test the brakes. The operator tests the brakes by raising the load only a few inches off of the ground and applying the brakes. There should be no drift in the hoist motion when the operator is not raising or lowering the load. This is an excellent safety measurement and should be used.

Many factors are taken into account when considering the safety factor for your crane. There are so many different parameters that get you to your true safety factor that you would have to re-engineer the entire crane to figure out what it truly is. Once true stress is calculated at its maximum on all load bearing components and the usage of the crane is calculated then the true safety factor can be calculated. The standards are guidelines to help with the design of the crane. However, they also give limits and requirements for most vital crane components. Although cranes may be built according to CMAA standards, all electric hoists are designed and rated according to FEM standards. These standards are in place to make the operator and those working around the crane safe. Be safe and never exceed the capacity of the crane. Ensure your crane operator has been properly trained and your equipment is being inspected as well as maintained with a through preventive maintenance program.

Load Testing Reinstalled Equipment in the State of California.

Recently I had a customer who wanted to have load testing done on his monorails. His monorails were three ton capacity. Now, Load testing in the State of California is required on initial installations and every four years for equipment over three tons. However they often move the hoist to different locations and on different monorails throughout the facility. The question that arose was if we had to load test them every time a hoist gets re-installed on a different monorail.

In a letter from 1994 written by CAL-OSHA they state that if the hoist is not an integral part of the machine, then the monorail does not have to be load tested or certified. Then they go ahead and define a monorail as “a crane whose hoisting mechanism is suspended from, and is an integral part of, one or more trolleys mounted on a single track.” So what the heck does integral mean anyway? OSHA commented to us that this is a confusing part for people trying to interpret what the regulations mean, and I can definitely see why. CAL-OSHA does not explain what they are referring to with the word, “integral”. Even under the definitions it is not listed. What he told us was that if it is not defined in Title 8 then it should be referenced from a dictionary. He went on and referenced Webster’s Dictionary and stated that the term integral as, essential to completeness, 2. Composed of integral parts, 3. Lacking nothing essential. So what I gather from this is that all hoists are integral to any monorail.

The following is an excerpt from the email sent to us from CALOSHA. , A hoisting unit is integral to all monorail cranes. Without a hoisting unit, a monorail crane is not complete and cannot perform its intended function. Section 5022 requires that a proof load test be performed on a monorail crane every four years. It is silent when it comes to reinstalling the hoisting equipment on the monorail crane. ASME B30.11 requires an operational test on reinstalled equipment. It also says that a load test should be performed on reinstalled equipment as determined by a qualified person. The problem is that our code in 4884 requires that such cranes be designed, installed, and constructed to the ASME requirements. Cranes need to be inspected, tested and maintained per Title 8. Since Title 8 is silent on the issue of reinstalled equipment, my opinion is that a load test should be performed based on your recommendation. What does the manufacturer recommend?

So, in the end it is up to the manufacturer’s or crane servicing company’s recommendation. Now he did state that he suggest a load test be performed every four years per Title 8 5022, and a load test on reinstalled equipment be performed as determined by a qualified person as per ASME B30.11. However I don’t really get it. They put all these regs in place and state all these regulations that are required to be followed on all equipment over three tons. Then when asked about it they pretty much say below three tons it should be done as well but it is up to the discretion of a qualified person. I thought that these regulations were in place to keep people from using their own discretion? If my customer comes to me with these questions, I would recommend quarterly inspections on all their equipment but only load testing above 3 ton capacities unless it is a class C or D crane then I would recommend every four years as well. Anything below three ton it really depends on the severity of use of the crane or hoist. If it is used a lot then it really needs to be treated as a piece of equipment that has a capacity over three tons. I’ll leave you with this, do you really think 6,000 lbs is going to hurt any worse than 8,000 lbs?