Jaw crushers,double-toggle jaw crusher

There have been numerous kinds of jaw crushers developed and built considering that the initial US patent was issued in 1830. They fall into 3 groups: Blake form (double toggle), Dodge form, and single toggle (overhead eccentric). The Blake-type double-toggle crusher and the single-toggle crusher, however, dominate the market.

The double-toggle crusher is preferred for heavy-duty crushing on hard material. It is heavier and more expensive than a single-toggle crusher for a given duty. Justification for selecting a double-toggle crusher will therefore be needed for each application. Some of the factors in this analysis are:

1. Compressive strength of the rock.

2. Work index.

3. Feed size and reduction ratio.

4. Abrasion index.

5. Life of the mine.

6. Capital cost.

jaw crusher

The size of a jaw crusher is measured by its feed opening (gape) and length. For example, 610 by 914 mm (24 by 36 in.), or 2436, indicates a distance of 610 mm (24 in.) from fixed jaw plate to moving jaw plate where the feed enters, and 914 mm (36 in.) is the dimension across the jaw plates.

jaw crushers description

Double-toggle Jaw Crusher—The double-toggle crusher drives the moving jaw through an eccentric shaft, which moves the front and rear toggles up and down at each revolution of the

shaft, closing the jaws on the downstroke and opening them on the upstroke. The toggles are held in the toggle seats by the spring-loaded tension rods. Minor setting changes to the crusher

are made by changing shims between the main crusher frame and the rear toggle block. Major adjustments are made by changing the length of the front toggle.

Crusher Sizing—Jaw crushers are sized on the basis of the maximum lump size to be crushed and/or the tonnage rate to be crushed. Maximum lump size should not exceed 80% of the gape. For example, a 610- by 914-mm (24- by 36-in.), or 2436 crusher, will accept a maximum lump size of 610 by 0.8 = 488 mm (19 in.). In actual operations, the crusher will occasionally accept lumps up to the gape size, as long as bridging does not occur.

In open pit operations, the maximum lump size may be controlled by the size of the shovel dipper. Under these circumstances, a guide to crusher size can be obtained from Table 25.3.1.1.

Approximate capacities of double-toggle jaw crushers are available from crusher manufacturers and are provided in Table 25.3.1.2.

Single-toggle Crusher—This form of crusher is also called an overhead eccentric crusher. Reference to Fig. 25.3.1.2 will illustrate the reason for this name. The overhead eccentric is an

integral part of the moving plate, which moves up and down with the rotation of the eccentric. The single toggle is pivoted at the base of the moving plate and causes the jaw to move in an

arc. This results in a pinching action between the moving and stationary plates. The toggle is held in the toggle seats by the compression spring. Major adjustments to the crusher setting are made by changing the toggle length. Minor adjustments are made by changing shims between the toggle block and the mainframe. The toggle is developed to shear or break in the event tramp material enters the crusher.

The single-toggle crusher is of much lighter construction than the double-toggle Blake-type crushers. For example, a 610 by 914-mm (24 by 36-in.) single-toggle crusher weighs about 14,512 kg (32,000 lb), whereas a double-toggle crusher of the same size weighs 25,678 kg (65,000 lb).

CRUSHER SIZING. Similar to the double-toggle crusher, the single-toggle crushers are selected either on the basis of maximum lump size to be crushed, or the tonnage rate to be crushed, or both.

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