Ellicott Dual Wheel Cutter Designed to Mine Clay-Bound Materials
In the late 1980’s, Ellicott International placed its first dual wheel cutter in service at a Baltimore area sand and gravel plant.
The purpose of the application was two-fold: first, to demonstrate and establish the effectiveness of this new type of excavator and, second, to improve the performance of a 15-year-old 10" Ellicott Series 400 "DRAGON™".
Free Trial
The installation was made on a no-charge basis for a 60-day initial operation period after which the customer was free to purchase the excavator or return it to Ellicott.
The dredge on which the dual wheel cutter was placed had originally been equipped with a 50 hp rotary type basket cutter equipped with spade-type teeth. Due to the very cohesive nature of the deposit, a mixture of sand and kaolin clay with occasional layers of iron cemented sandstone, the performance of the dredge had been less than the customer had hoped for.
Prior to installing the new dual wheel cutter the long-term solution had been the use of a large Caterpillar bull dozer to push loosened material to the dredge while four other pieces of equipment, specifically a drag line, a large front end loader, and two large dump trucks had been utilized to provide the additional required material.
After the initial trial period of the dual wheel excavator, the customer elected to purchase the new unit.
Subsequent to this, the bulldozer, the front-end loader, two dump trucks, and the dragline were removed from service along with the operating personnel. The dual wheel cutter met all the hopes of the customer.
New Design
Previous wheel excavators have, to one degree or another, suffered from an inability to dig clay-bound material without significant problems caused by plugging with clay. Ellicott with its widely spaced buckets and internally mounted water powered flushing system overcame the majority of these problems.
Other bucketwheel units, with closely spaced buckets and no effective method to achieve forced clay extraction, had not been as successful. Notwithstanding this, the company was not satisfied with the additional power requirement to maintain plug-free operation of its bucketwheel and as a result, sought another solution.
The dual wheel cutter proved satisfactory during operation in heavy clay material, specifically by taking advantage of a one-sided bucket system coupled with a rigid hopper back plate. These two features, the first a single-sided bucket which provides no stacking area for the clay, and the second a rigid hopper back which wipes any material from the digging side of the bucket mechanism, provide plug proof operation.
Beyond this, in an effort to minimize the potential of wear and tear normally associated with its original design, the new wheel has simplified the complexity of the original wheel.
A centrally mounted drive mechanism is placed between the two rotating bucket elements with the drive motor being placed to the rear and entirely away from the area of excavation. The suction pipe is located under the drive mechanism and enters straight into the suction hopper located between the two rotating elements of the excavator.
Field Results
The system has operated on a continuous basis served by a 10-inch dredge pump system. In heavily bound sandy clay it has operated at 200-250 tons per hour production rate.
In loose and free-flowing material, the production rate has been in the 350-500 ton per hour range. Ellicott feels this excavator will supersede the older style bucketwheel excavator, principally due to its simplicity and ease of maintenance coupled with the plug-free operating capability.
The new mechanism reflects the continued search by the dredging industry for improved and more efficient methods of accomplishing the task of underwater excavation. The double wheel excavator represents another innovation by Ellicott. Its success ultimately extended the useful life of the dredge by ten years!
Reprinted from World Dredging & Marine Construction
