Cat B-Series Mobile Shears Feature New Jaw Design

Tue March 17, 2009
Forestry Equipment Guide

Three new Cat B-Series mobile shears — S320B, S325B and S340B — round out the six-model lineup of Caterpillar designed shears. The new shears feature a redesigned lower jaw, wider jaw opening, new knife-retention system, new jaw-adjustment system, greater hydraulic power and boom or stick mounting options. The overall design assures optimum productivity, reliability and serviceability in the toughest metal reduction applications.

The new Cat B-Series models, featuring a 360-degree hydraulic-rotation system, match the capabilities of a broad range of Caterpillar hydraulic excavators used in scrap-metal processing and in demolition operations that require reduction of large structural elements.

Among the features of the new shears is the straight lower jaw, which flattens beams, pipes and columns and distributes the material evenly along its entire length. Most shears use a lower jaw with knives that angle downward to the midpoint of the jaw, forming a triangular-shaped opening (apex). Conventional shears, with an apex in both the upper and lower jaws, tend to concentrate the mass of material in the center of the jaw, thus increasing cutting difficulty. The new straight lower jaw used with Cat B-Series shears prevents material concentration, and in doing so, effectively enhances cutting force, according to the manufacturer.

Increased hydraulic power in the new Cat B-Series models allows a wider jaw opening to handle a greater volume of material, such as large structural steel pieces, large diameter pipe and bundles of pipe. In addition, the larger opening provides improved visibility for the operator when working at a distance and aligning the jaws around material.

High-strength retaining bolts thread directly into the knife sections of both the upper and lower jaws. Bushings around the bolts help prevent loosening, and a slotted shim plate, which slips over the bushings, simplifies knife changes. The four main knives, plus the side and front knives, are fully reversible and provide four long-lasting cutting edges. The weld-on piercing tip at the end of the upper jaw is made of hardened steel. The tip can be repeatedly hardfaced (or easily replaced) to maintain upper jaw effectiveness.

The Cat B-Series shears also feature a newly designed adjustable hub to maintain an optimum cutting position between the upper and lower jaws as the knives wear. The new hub uses thicker (5 mm) shims for easier adjustment and has a new bolt-retention system that keeps the assembly tight.

In addition, a new housing protects the jaw cylinder through its complete cutting cycle, and a replaceable (bolt-on) wear plate protects the outside of the upper jaw. Large access panels (top, bottom and sides) and a jaw service lock assure fast and safe routine maintenance.

The new models, as do all Cat B-Series shears, feature an integrated speed valve that reduces cycle time. The 360-degree rotation system minimizes machine repositioning, thus reducing undercarriage wear and causing less surface disruption.

Generally, Cat shears are boom-mounted (pinned directly to the carrier’s boom tip) for scrap processing and for operations in which machine reach is not critical. In applications requiring significant reach, such as demolition, the shear normally mounts to the carrier’s stick (digging arm).

Stick-mounting options include pinning directly, or, depending on the excavator model and specific stick, using a dedicated or pin-grabber-type coupler.

This story also appears on Construction Equipment Guide.