Although this is a topic that many of our customers are familiar with, the proper use and care of hydraulic lock nut rams is something that still causes some confusion on the job sites where they’re used.
Lock nut rams carry tremendous benefits for varying projects ranging from raising a bridge, lifting concrete foundations to allow for replacement of dampers and supports or for simply raising heavy equipment that requires extended periods of lift without the use of cribbing.
With that versatility, however, breeds the possibility for misuse or complacency in performing the lift. While the lock nut rams allow users the ability to remove the hydraulic system once the load is raised and keep the load in place, there are still safeguards that should be followed, for example, never being stationed under the load during jacking operations. These guidelines, detailed below, help to ensure safe jacking practices that will not only uphold the safety of the workers and project, but also safeguards the equipment from taking on damage that may require the ram be removed from service.
One key characteristic of lock nut rams is the ability of the head to pivot +/- 5 degrees at height, allowing the load to maintain 100 percent contact while raised. While that feature typically functions as a benefit to the workers on site, if not adjusted before lowering the load back down, it can also inflict a great deal of damage to the ram itself that may not be repairable.
Along the length of the cylinder, threads are milled into the side, allowing the lock nut to be spun down the shaft to secure it in place. These threads tend receive the most damage from side-loading during the lowering of the ram, causing the cylinder to run along the rim of the housing, flattening the threads. This damage can, if severe enough, incapacitate the locking feature of the ram and render the ram damaged beyond repair. The cylinder threads will also score the interior housing of the ram and leave deep grooves that cannot be repaired. In cases when the ram’s housing is grooved, the ram completely loses the ability to create a seal around the inside of the casing, allowing fluid to seep out and rendering the ram useless for its intended capacity. Damaged threads can sometimes be repaired, which creates unexpected costs that could be avoided by following procedures to limit the movement of the head during the lifting and lowering phase of the lift.
One of the easiest steps to take to avoid causing damage to rams during operation is to verify, prior to raising the load, that the surface you’re placing the ram on can withstand the force of the load throughout the lift. It’s imperative that the rams remain plumb and level from start to finish, so this step is extremely important. One of the most common problems is when the ground shifts below the ram, causing the cylinder head to lose full contact with the load. The cylinder head of the ram must maintain 100 percent contact with the load at all times to avoid accidents on the job site.
One tip that is advisable for the safety of both employees and the equipment when using lock nut rams is to incorporate the use of cribbing throughout the lift that can be used in conjunction with the lock nut rams or in place of the ram once the load is raised up. It is important to ensure the cribbing used is able to withstand the entire force of the load being raised. The use of cribbing allows for you to increase the surface area of the support, thereby spreading the load across a wider area and lessening the strain on the ground below the jacks.
Think of it this way: when working on your car doing an oil change or changing brakes, you would never work below the car without having a jack stand underneath, your parking brake on and a chock block behind your wheels as a way of protecting yourself from the possibility of experiencing a failure of the jack being used to lift your vehicle off the ground. That same mentality should be applied when working with lock nut rams to avoid having any catastrophic issues with the cribbing playing the role of the jack stand, the lock nut as the parking brake and an additional safety check valve serving as the chock block behind the tires.
One other important note to make with lock nut rams, especially in the case of low-profile pancake rams, is to ensure that the plunger is not jacked further than intended max stroke. On low-profile pancake lock nut rams specifically, there is no mechanism in place that will stop the plunger from being jacked completely out of the housing. As a result, these rams all include a yellow or red strip on the piston itself that tells you when to stop lift to avoid having the plunger from raising out of the housing.
You can imagine that amount of damage that can be created to the ram if the cylinder is pushed beyond that mark and pushes out of the housing. Not only does the ram take on a great deal of damage, but the piece of equipment that it was being used to lift is undoubtedly going to be damaged as well, not to mention any potential injuries that may arise.
While LGH takes pride in having the safest, highest quality and best maintained lifting and rigging equipment the rental industry has to offer, there are always factors that can create the potential for job site issues. Taking the time to familiarize yourself with the proper use of each piece of equipment and instilling these additional safeguards to your next job site can mean the difference between having your job run smoothly or having an issue.