The next generation of heavy construction equipment has arrived, as two of the world’s largest suppliers have moved toward hybrid construction vehicles.
Manufacturing giants Caterpillar Inc. and Komatsu Global are both set to release new products that are powered by hybrid-electric drives. For Caterpillar, the world’s largest manufacturer of construction equipment, this will be their first foray into the use of hybrid drive technology in their earth-movers. Komatsu is already on their second-generation of hybrids.
Traditional mechanical and hydraulic systems in heavy construction equipment are being replaced by these more efficient and environmentally friendly ones. As an added bonus these products cut down on operating costs because fuel prices are so high and traditional construction equipment uses up so much of it.
With nations all over the world are looking to cut down on carbon emissions at the same time that they want to spend more on infrastructure and construction projects, now is the perfect time for hybrid earth-movers to emerge as an ideal solution to both problems.
Hybrid drives can dramatically improve fuel efficiency since they use smaller diesel engines and operate at speeds that maximize the best possible results. Drives can also recover and reuse excess energy that used to be given off as heat in traditional systems. This means smaller cooling systems, lighter equipment, less friction, and longer shelf-lives.
These smaller and lighter designs can boost fuel efficiency by up to 40% when compared to traditional equipment.
Caterpillar Inc is set to begin producing the D7E Bulldozer with a hybrid electric drive. This is the construction manufacturing industry’s first alternating-current (AC) electric-drive, track-type tractor. This vehicle’s design eliminates the need for the mechanical transmission and torque divider used in the company’s D7R.
Eliminating the torque divider along with keeping the engine running in a narrow range of speeds provides the Caterpillar D7E with its biggest boosts in fuel reduction. However there are other features that add to its efficiency.
Instead the D7E uses a locomotive-style hybrid drive-train to power itself. Its diesel engine found in the front of the cab is used to drive a brushless-ac generator that powers the Caterpillar D7E’s two electric motors.
The electric currents from this generator are rerouted into a solid-state power inverter and then on to the two ac-electric motors that are connected to the differential steering system, propelling the tracks.
"We evaluated all of the current applications for the D7R and purposely set out to build an electric-drive machine that can do all of the same things, and work in all the same environments, that the power-shift machine currently can do," says Dave Nicoll, commercial manager in Caterpillar’s Tractor Products Department.
This propulsion module has absolutely no moving electrical contacts, significantly improving the machines durability and function. Also because power flows from the generator to the electric drives through cables, rather than a hard drive shaft, the tractor’s heaviest components can be optimally positioned inside the frame to give it improved balance.
With relatively few moving parts compared to traditional mechanical engines, the D7E has dramatically reduced traction. Also the Caterpillar D7E’s motor is sealed and liquid cooled, making it resistant to the rugged environments that construction equipment is exposed to.
This reduces heating and makes this hybrid drive system have increased longevity while requiring very little maintenance.
With a net power output of 235 horsepower and 100,000 pounds of pulling power this new hybrid model lives up to its logo, “Move earth and save the Earth.”
Komatsu Hybrid HB215LC-1
In 2008 Komatsu, the world’s second largest producer of heavy construction equipment, released the world’s first hybrid-drive heavy equipment construction vehicle. The PC200-8 Hybrid Excavator was a huge success and the lessons learned from it have cleared the way for the newest generation of hybrid drive technology.
The company will take things to the next level later this year when they release their second generation hybrid, the Hybrid HB215LC-1 hydraulic excavator.
“We’re bringing out our second-generation hybrid excavator before any of our top competitors introduce their first,” says Erik Wilde, Vice President of Product Marketing for Komatsu. “We took our last three years of experience in the market to further optimize the system. Another key improvement is the new ability to run hydraulic attachments.”
How it Works
The HB215LC-1 Excavator has three main components to its hybrid drive system that allow it to be one of the most advanced and efficient pieces of construction machinery ever manufactured.
Its design incorporates an electric swing motor, an Ultra-capacitor, and a generator. Electricity is stored in the Ultra-capacitor, which can send energy to the electric swing or to the generator/motor to power the engine.
The key feature is that the electric swing motor generates and stores electricity during swing braking, which is then reused by the capacitor. Regenerating its own energy is what allows the hybrid excavator to be more efficient and increase fuel savings.
The 20-ton hybrid excavator reduces emissions and averages fuel savings of 25% when compared to traditional heavy construction equipment of the same size. That equals the emission reduction equivalent of 14 hybrid cars on the road.
In the average work year the HB215LC-1 hybrid excavator will save its operators the equivalent of 1,500 gallons of diesel fuel or 6,300 gallons of crude oil, and will give off 25% less CO2 emissions than a standard excavator without hybrid technology.
The hybrid excavator also features an advanced Komtrax computer system to keep it running in prime condition. A remote monitoring system provides key information to the machine operator to help them monitor efficiency and spot potential problems before they arise.
Maintenance reminders and warnings of overheating ensure that the equipment isn’t overused. A panel also displays current fuel consumption as well as daily fuel consumption, allowing operators to make sure that they are getting the best possible use out of their equipment.