Jaw Crushers
Jaw Crushers are a compression-type machine that crush material between a moving piece of steel and a stationary piece of steel. They are used for primary and sometimes secondary size reduction.
Applications
Jaw Crusher Models
The Jaw Crusher was first introduced by Eli Whitney Blake in 1858 as a double-toggle Jaw Crusher. Introduced in 1906, McLanahan’s Universal Jaw Crusher was one of the first modern era overhead eccentric Jaw Crushers. On the overhead eccentric style Jaw Crusher, the moving swing jaw is suspended on the eccentric shaft with heavy-duty double roll spherical roller bearings.
The swing jaw undergoes two types of motion: one is a swing motion toward the opposite chamber side (called a stationary jaw die due to the action of a toggle plate), and the second is a vertical movement due to the rotation of the eccentric. These combined motions compress and push the material through the crushing chamber at a predetermined size.
While Jaw Crushers are mostly used as the first stage of material reduction in systems that may use several crushers to complete the circuit, the Jaw Crusher has also been used as a second-stage crushing unit. Depending on the application requirements, Jaw Crushers can be used in stationary, wheeled portable and track-mounted locations. The Jaw Crusher is well suited for a variety of applications, including rock quarries, sand and gravel, mining, construction and demolition recycling, construction aggregates, road and railway construction, metallurgy, water conservancy and chemical industry.
How Jaw Crushers Work
A Jaw Crusher uses compressive force for breaking material. This mechanical pressure is achieved by the crusher's two jaws dies, one of which is stationary and the other is movable. These two vertical manganese jaw dies create a V-shaped cavity called the crushing chamber, where the top of the crushing chamber is larger than the bottom. Jaw Crushers are sized by the top opening of the crushing chamber. For example, a 32 x 54 Jaw Crusher measures 32" from jaw die to jaw die at the top opening or gape opening and 54” across the width of the two jaw dies.
The narrower bottom opening of the crushing chamber is used to size the discharge material. A toggle plate and tension rods hold the pitman tight near the bottom of the moving swing jaw. The toggle plate is designed to perform like a fuse and protect the crusher in the event that an uncrushable material enters the crushing chamber. As a rule, Jaw Crushers have a 6:1 or 8:1 ratio for crushing material. Still using the 32 x 54 Jaw Crusher example, the top size of the feed entering the crushing chamber has to follow the F80 rule that 80% of the top size feed material is smaller than the gape opening. Using the F80 rule with the 32 x 54 Jaw Crusher, the 32” gape opening equals a 26” top sized feed, and with the 6:1 ratio of reduction, the discharge setting would be around 4”.
Since the crushing of the material is not performed in one stroke of the eccentric shaft, massive weighted flywheels are attached to the eccentric shaft and powered by a motor. The flywheels transfer the inertia required to crush the material until it passes the discharge opening.
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Why McLanahan Jaw Crushers
More than 110 years of engineering and customer service experience keep customers running to McLanahan to meet their production goals. McLanahan Jaw Crushers are proudly made in the USA and have imperial designs. With our grass roots design coupled with listening to customer needs for product enhancement over the years, McLanahan offers traditional hydraulic-shim adjustment Jaw Crushers as well as H-Series Jaw Crushers that feature hydraulic discharge setting adjustment, adjust-on-the-fly chamber clearing in the event the site loses power (once power is restored) and hydraulic relief for overload events with auto-reset.
Whether the traditional hydraulic-shim adjustment or the H-Series Jaw Crushers, both machines have an aggressive nip angle that provides consistent crushing throughout the entire crushing chamber, which leads to increased production and less downtime on maintenance.
With years of engineering experience, McLanahan is able to recommend and provide the correct Jaw Crusher for your application.
Frequently Asked Questions About Jaw Crushers
Ask An ExpertThe information below will determine the size Jaw Crusher for most applications:
- Maximum material lump, or largest size expected to be crushed
- Tons per hour rate needing to be crushed
- Desired size of discharge material needed
- Operating hours per day.
F100 is the maximum gape opening on a Jaw Crusher. F80 is the feed size to the Jaw Crusher, calculated by taking 80 times the gape opening divided by 100. P80 is the percent passing the closed side setting in tph.
The Jaw Crusher is designed to handle this feed, but limits are:
- Do not exceed the F80 rule on top size. This happens at times, just not a steady rate.
- The fine material size equal to the closed side setting should be removed prior to entering the crushing chamber.
A best practice, if possible, is to blend the material arriving from the source. This will ensure a constant and well-graded feed to the crushing chamber. In turn, this will produce a steady rate of tph and promote inter-particle crushing that helps break any flat or elongated material. It also aids in equal work hardening the manganese jaw dies and prolonging the life of the jaw dies.
Usually a Jaw Crusher is in an open circuit, but it can be used in a close circuit if the return load is not greater than 20% of the total feed and the raw feed is free of fines smaller than the closed side setting.
Both the shim and hydraulic styles of adjustment perform the same task. Below is a list of items to help decide which is right for you.
- If your Jaw Crusher's closed side setting is adjusted once every six months or greater, a traditional shim adjust may be a better investment.
- If making adjustments to your Jaw Crusher's closed side setting more frequently, less time spent can be spent on adjustment by using push button controls and more time can be allotted for production.
- If your site experiences power losses and you have spent half a day digging out the crushing chamber and trying to restrain the flywheels so the moving swing jaw does not rotate to the relaxed position with a worker in the crushing chamber, the chamber can be cleared safely from the outside with the aid of hydraulics in about one hour once power has been restored.
- H-Series Jaw Crushers still use a toggle plate that has the dual purpose of transferring the crushing action and a fuse to protect the crusher's major components. Also used are off-the-shelf bank hydraulic cylinders which provide for tramp iron relief with auto-reset to the last stored set point of the closed side setting.
With decades of engineering experience, McLanahan is able to provide the correct Jaw Crusher for an application.
Features & Benefits
- Rigid one-piece fabricated base frame for unmatched durability and strength
- Massive cast steel pitman for brute shock loads
- Deep crushing chambers and large eccentric shafts offset combined with a steep toggle angle yield more compressive force throughout the crushing chamber
- Large balanced flywheels supply continuous inertia to the crushing action
- Lock pins on each side of the base frame hold the pitman safely for maintenance
- Reversible manganese jaw dies for long-life use
- Toggle plate is designed as a fuse to protect the crusher from a tramp iron event
- H-Series Jaw Crushers offer the addition of hydraulic discharge setting adjustment, chamber clearing and automatic tramp iron relief with auto-reset