What is the difference between single-cylinder and multi-cylinder crushers?

1. Structural Comparison

Single-Cylinder Hydraulic Cone Crusher
Mainly consists of six major assemblies:

1. Upper Frame Assembly: Upper frame, concave ring, distributing cap, upper frame guard plate.

2. Lower Frame Assembly: Lower frame, lower frame guard plate, lower frame liner, eccentric bushing, sealing cylinder.

3. Moving Cone Assembly: Main shaft, moving cone body, mantle.

4. Transmission Shaft Assembly: Sheave, transmission shaft, bearings, transmission shaft frame, pinion.

5. Eccentric Sleeve Assembly: Counterweight ring, eccentric sleeve, gear, main shaft bushing.

6. Hydraulic Cylinder Assembly: Upper friction disk, lower friction disk, hydraulic cylinder, cylinder sleeve, cylinder bottom, position sensor.

Multi-Cylinder Hydraulic Cone Crusher
Primarily includes the following six major parts:

1. Lower Frame Section: Frame, main shaft, guide pin.

2. Eccentric Sleeve Section: Eccentric sleeve, balance ring, gear.

3. Transmission Section: Transmission shaft, pinion, shaft sleeve.

4. Support Sleeve Section: Support sleeve, locking cylinder, lock nut.

5. Adjusting Ring Section: Adjusting ring, concave ring.

6. Moving Cone Section: Body, mantle, hammerhead, spherical seat.

2. Discharge Opening Adjustment Comparison

Single-Cylinder
During normal operation, the discharge opening size is adjusted by injecting or draining oil from the main shaft hydraulic cylinder via an oil pump, causing the main shaft to move up or down (main shaft floats). This adjustment method may make it difficult to lock the discharge opening securely when crushing hard ores.

Multi-Cylinder
The adjustment is achieved via a hydraulic pusher or hydraulic motor, which adjusts the adjustment cap, thereby rotating the adjusting ring within the support sleeve (the fixed cone screws up or down). The advantage of this method is that the discharge opening can be easily and securely locked.

3. Overload Protection Comparison

Single-Cylinder - Tramp Iron Release & Cavity Clearing
When tramp iron passes through, hydraulic oil flows into an accumulator, lowering the main shaft. Afterwards, the accumulator returns the oil, and the crusher resumes operation. The hydraulic pump is also used for cavity clearing.

Multi-Cylinder - Overload Protection
When non-crushable material enters or the machine overloads, the hydraulic safety system activates, increasing the discharge opening to eject the material. If material gets stuck, the cavity clearing system further enlarges the opening. The system then automatically resets.

4. Lubrication System Comparison

Single-Cylinder
Two oil inlets: one enters from the bottom of the main shaft to lubricate the spherical bearing, spherical seat, frame bushing, and main shaft bushing, then lubricates the gear and pinion. The other inlet lubricates the transmission shaft bushing. Both oil paths share a common outlet.

Multi-Cylinder
One oil path enters from the lower oil port, reaches the main shaft center, and splits into three branches: lubricating the eccentric sleeve's inner/outer surfaces, passing through the main shaft's central hole to the spherical bearing, and lubricating the gear and pinion via passages. Another path enters via the transmission shaft frame to lubricate the transmission bearings, with return oil passing through ports below the pinion and on the dust cover.

5. Crushing Force Component Comparison

Single-Cylinder
Similar to spring cone crushers, the main shaft and moving cone are combined and supported by the spherical seat. Thus, the main shaft and moving cone are supported as a base unit, and the eccentric sleeve drives the main shaft to provide crushing force.

Multi-Cylinder
The main shaft of the multi-cylinder crusher is short and stout, allowing for a larger diameter design. It stands directly on the frame (not inside the eccentric sleeve) and is directly supported by the frame, providing higher load-bearing capacity. The eccentric sleeve directly drives the moving cone to provide crushing force.

The different mechanical structures determine how the frame experiences stress during crushing: the single-cylinder frame withstands tensile stress, whereas the multi-cylinder frame withstands reduced tensile stress. Thus, the multi-cylinder crusher has advantages in frame construction.

6. Wearing Parts Comparison

Single-Cylinder

• Non-Standard Wearing Parts: Bushings, oil seals, concave ring, shaft sleeve, press cap, cutting ring, mantle, dust seal, upper/lower friction disks, oil retaining ring, frame bushing, middle friction ring, eccentric bushing.

Multi-Cylinder

• Standard Wearing Parts: V-belts, skeleton oil seals, O-rings, dust seals, Yx-shaped seals, Yz-shaped seals.

7. Counterweight Principle Comparison

This is because, in a single-cylinder crusher, when the main shaft and moving cone swing towards the closed-side, the thick part of the eccentric sleeve is on the open-side. At this point, the center of gravity of the entire moving cone shifts towards the closed-side. Therefore, a counterweight is added to the thick part of the eccentric sleeve to balance the moving cone assembly. Furthermore, when the main shaft and moving cone swing towards the closed-side, material accumulates on the open-side, creating resistance against the moving cone's swing towards the open-side. The counterweight helps the moving cone swing back towards the open-side more easily.

In a multi-cylinder hydraulic cone crusher, the main shaft is stationary. Therefore, the counterweight only needs to balance the eccentric sleeve itself.

8. Feeding Method Comparison

Generally, both single-cylinder and multi-cylinder hydraulic cone crushers can accept full-chamber feeding. The latter's high load-bearing capacity allows it to handle full feeding without issues. Utilizing the interparticle crushing principle, rocks are crushed and compacted simultaneously within the chamber, providing a shaping effect alongside crushing, resulting in excellent product shape.

It's important to note that full-chamber feeding means the crushing chamber is filled with material. This ensures high crushing efficiency while also promoting even wear on the liners.

9. Crushing Effect Comparison

The multi-cylinder hydraulic cone crusher produces a higher content of fine particles at fine crushing settings, offering better fine-crushing efficiency and superior interparticle crushing performance. The single-cylinder hydraulic cone crusher, on the other hand, is better suited for secondary crushing, offering higher throughput capacity.

10. Actual Production Capacity Comparison

When crushing soft and weathered ores, the single-cylinder crusher's advantage of high throughput is prominent. However, when crushing medium-hard and hard ores, the multi-cylinder crusher performs more remarkably.

For fine crushing of medium-hard and above ores, a multi-cylinder crusher of the same specification can typically produce more finished product. Generally, the harder the ore, the greater the difference in output between the two types.

11. Operation and Maintenance Comparison

Single-Cylinder: Simple structure and reliable performance: Features a single hydraulic cylinder, resulting in a simple and compact structure, low failure rate, and low production cost (simpler mechanical systems generally have lower failure rates, higher reliability, and more stable operation).

Multi-Cylinder: Top-side serviceability for quick and easy maintenance: All parts can be disassembled and maintained from the top or side. The moving cone and top assemblies are easily removed and installed without dismantling the frame or loosening foundation bolts, making routine replacements more convenient.

Summary

In conclusion, both single-cylinder and multi-cylinder cone crushers are high-performance machines, but their structural differences lead to distinct advantages and disadvantages. Compared to the single-cylinder type, the multi-cylinder crusher holds advantages in structural performance, maintenance ease, and crushing efficiency. Correspondingly, the price of a multi-cylinder hydraulic cone crusher tends to be higher, which is a key consideration for users during selection.

Note: Currently, some multi-cylinder crushers from smaller manufacturers are merely modifications of Symons cone crushers, where the springs are replaced with hydraulic cylinders while the internal structure remains the same (essentially still a Symons design). Users should be cautious when selecting equipment.