This week, we continue our review of the white paper “How to Size a Worm Gear Screw Jack” by looking at the role Tonnage under load can affect the sizing of the linear motion system.
The load capacity of a jack is also limited by the physical constraints of its components, such as its drive sleeve, lift shaft or bearings. All anticipated loads should be within the rated capacity of the jack. Loads on the jack in most applications include: static loads, dynamic (or moving) loads, cutting forces or other reaction forces and acceleration/deceleration loads.
For shock loads, the peak load must not exceed the rated capacity of the jack, and an appropriate design factor should be applied that is commensurate with the severity of the shock.
For accidental overloads not anticipated in the design of the system, jacks produced by Nook Industries can sustain the following overload conditions without damage: 10 percent for dynamic loads, 30 percent for static loads.
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The following is taken from an excellent white paper from Ron Givannone, Director of Application Engineering and Business Operations at Nook Industries (hyperlink). Titled “How to Size a Worm Gear Jack,” it looks at the key factors in figuring out what size and configuration of jack will work based on the needs of your application. Over the next few weeks, we’ll look at the different factors, and offer a bit more background.
This week, how Horsepower limitations can affect jack sizing.
When determining the lifting power of a jack, it’s a common mistake to assume the lifting capabilities of a jack are determined solely by its tonnage size. The load’s capacity is more often determined by its horsepower limitations. For example, a 10-ton jack may only be able to lift a one-ton load, because it is temperature-limited by the working horsepower it requires to lift the load.
The horsepower limit of the jack is a result of its ability to dissipate the heat generated from the inefficiencies of its components. The maximum horsepower value represents the point at which the heat that is generated by the working horsepower to move a given load meets the maximum temperature of the internal components. The working horsepower to move a given load is calculated by using the following formula:
How well a jack can dissipate heat is influenced by many application-specific variables, including mounting, environment, duty cycle and lubrication. The best way to determine whether performance is within horsepower limits is to measure the jack temperature. The temperature of the housing near the worm gear must not exceed 200 degrees Fahrenheit.
Looking for help in figuring out the right horsepower? Here are some tools:
Calculate Horsepower with this calculator
Worm gear jacks definitions and technical data
Just a click away are over 20 linear motion videos. Want to learn the basics of a ball screw jack? Perhaps, you need to load a standard ball nut?
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Making Motion Happen
When a linear motion solution is in place & running, it’s easy for the casual observer to think it looks easy. That’s what our industry is all about; making the difficult or even impossible look easy.
But what few people outside the industry realize is just how much work needs to go into the design of a successful linear motion system. The old adage “Measure twice, cut once” doesn’t even begin to cover all the variables, that have to be dealt with.
Now, a new app looks to make that successful design at least a little easier. The Design Guide Pro not only offers selectors for Bevel Gears, Worm Gear Jacks, Bearings and Electric Cylinders, but it also has a calculator section. Here, you’ll find tools to help you establish Energy, Critical Speed, Column Load, Torque and Nut Life as well as helping with Unit Conversions.
All in the palm of your hand. Check it out today by clicking here.
Bevel gear jacks offer greater efficiency and rolling action than machine screw jacks, allowing for higher speeds or increased duty cycle. And there are no “standard” bevel gear jacks, each one is made to the specifications of the job. With this versatility, choosing the appropriate jack may be a long and tedious process. Until now…
Introducing the DesignGuidePro application from Nook Industries. The application makes for easy navigation when searching for design considerations for bevel jacks. Simply plug in the desired specifications, and the app will provide a list of products best-suited for the application.
DesignGuidePro puts the formulas in the palm of your hand; it’s free and user friendly. The application is compatible with both iOS and Android devices.
Make your bevel gear jack selections easier by clicking here.