The new Caterpillar 621H, 623H and 627H Wheel Tractor-Scrapers use an increased power and capacity, new structures, electronic controls and ergonomic design. The new H Series designs change the way wheel tractor-scrapers look, run and ride—and increase their capabilities to move material at the lowest cost per ton.
The new H Series machines replaced the equivalent G Series machines when commercial production begins in August of 2011. Each of the three models will be available with engines that meet US EPA Tier 4 Interim and EU Stage IIIB emissions standards and with engines for use in other regions.
The 620H Series Wheel Tractor-Scrapers maintain the G Series configurations. The 621H is a single-engine, open bowl machine; the 623H has an elevating scraper and a single engine; and the open-bowl 627H has twin engines—one on the tractor and one on the scraper—and all wheel drive. Capacities are increased 2 cubic yards (1.5 cubic meters) to 24 cubic yards (18.3 cubic meters) for the 621H and 627H.
The new bowl design is easier to load than the G Series bowl and has proven to enhance production. The 623H bowl maintains 23 cubic yards (17.6 cubic meters) capacity, but the elevator is stronger, more powerful and easier to adjust. The result is greater reliability and durability.
The new H Series wheel tractor-scrapers feature a more powerful engine in the tractor, and a more powerful engine in the scraper of the 627H. The Cat C13 engine in the tractor produces 407 hp (304 kW)—18 percent more power compared to the G Series. And the C9.3 on the 627H scraper produces 290 hp (216 kW), an increase of 19 percent from the G Series machine. The new torque converter coupled to the scraper engine is designed to put more power to the ground. The 8-speed planetary powershift transmission hardware is the same as the G-Series unit, but new controls and software drive greater performance.
The new brakes are similar to Cat off-highway truck brakes and deliver predictable and durable stopping power. The H Series machines also introduce engine compression retarding and the elimination of hydraulic retarding.
Caterpillar offers three new integrated technology options on H Series Wheel Tractor-Scrapers. Sequence Assist is available on all three models and uses integrated software and position sensing cylinders to automate many of the tasks an operator performs when loading, hauling and dumping. Load Assist is available on the 621H and 627H models. As the machine enters the cut, the operator can activate Load Assist so the system takes over control of the cutting edge height, limiting tire spin based on integrated sensors and GPS technology to ensure consistent and full bowl loads.
Cat Grade Control is available on all three models and is designed to work seamlessly with Sequence Assist and Load Assist. Using satellite positioning technology, the system ensures cut protection by limiting how deep the scraper will dig.
The new cab is designed specifically to accommodate the tasks involved with operating scrapers. It’s 21 percent larger than the G-Series cab, which gives the operator more room for movement and allows more window area for an expansive view of the work area.