Everything about jaw crushers – what are they and how do they work?

In simple words, a jaw crusher is a hefty piece of equipment which is used to crush rocks. Jaw Crushers are primarily used in the mining and ore processing plants where the workers need to crush massive rocks. The origin of jaw crushers goes back to 1858 when inventor Eli Whitey Black first introduced this piece of machinery. With the passage of time, the use of jaw crushers has not remained limited to the pit and quarry industries; even the recycling businesses use them to reduce large materials.

Now, let’s see how jaw crushers work and what are the different types of jaw crushers that are commonly used in today’s time.

How do jaw crushers work?

A jaw crusher uses compressive force to break large sized materials into smaller and more usable pieces. With two jaws in action (one stationary and the other moving), jaw crushers create mechanical pressure which is potent enough to crush objects as solid as hard rocks. Both the jaws function in vertical orientation creating a V-shaped opening which is aptly called the crushing chamber where the to-be-crushed materials are put. Once activated, the opening between the jaws starts to taper down in the shape of a V and crushes the material.

The top opening of the crushing chamber is the measuring benchmark of a jaw crusher. So, if a jaw crusher is measured as 50” x 40”, it indicates that both the jaws are set 50” apart from each other and 40” is the width of both the crushers.

The major tasks performed by using jaw crushers are:

• Breaking down different kinds of ore
• Reducing building debris to pieces
• Rock crushing ranging from medium to extremely hard rocks
• Crushing large glasses

Types of jaw crushers:

There are two major types of jaw crushers – single-toggle jaw crushers and double-toggle jaw crushers. There are a few other types available like bulldog jaw crushers and force feed jaw crushers, but single-toggle jaw crushers and double-toggle jaw crushers are the most widely used machines in the mining industry.

Single-toggle jaw crushers:

Also known as overhead eccentric crushers, these machines operate with an eccentric shaft above them. The swing jaw plate that moves in an up-down motion houses the eccentric shaft. While in function, a single-toggle jaw crusher swivels at the bottom of the swing plate which makes the jaw move in an arc-like direction. Then the moving crusher compresses the material to be crushed against the fixed plate of the machine.

Single-toggle jaw crushers are available in heavy-duty and light versions and are built with stainless steel housings. High-grade forged steel is used to build the eccentric shaft and the moving jaw is built in either cast steel or welded variant. A compression spring aids the toggle on these crushers to stay in place. Small gap adjustment is taken care of by the shims as they are inserted firmly into the mainframe and toggle block.

Compared to double-toggle jaw crushers, single-toggle jaw crushers have less shafts and bearings on them. They only have one toggle that goes from the bottom of the swinging jaw back to the fixed point at the time of operating.

Double-toggle jaw crushers

In a double-toggle jaw crusher, the eccentric shaft moves the front and rear toggles up and down and drives the moving crusher. With every shaft revolution, the crusher jaw closes at the down-stroke and opens in the upstroke. A spring-loaded tension rod is used to keep the toggle in place. In this machine, the eccentric is mounted behind the swinging jaw. This is done to protect the eccentric shaft from getting damaged while the machine is in action.

The jaws on double-toggle crushers are like swinging doors that are placed vertically. There are two toggle plates here – one on the bottom of the eccentric arm and the jaw and the other at the opposite side of the eccentric arm.

Unlike the single-toggle machines that use rotary motion, a double-toggle jaw crusher functions by smashing hard objects between two massive jaw plates.

Conclusion:

The usage of jaw crushers has significantly changed the way mining and other industries used to function. It has cut down on efforts used to dismantle something as hard as rock or recycling larger size objects.