A number of OEMs are introducing electric-drive machines that power existing hydraulic systems.
There’s a slow and steady move toward electrification of construction equipment, including a focus on compact, battery powered machines. Concerns over the environmental effects of climate change have led many governments around the world to look to curb CO2 emissions. Legislative pressures for zero-emission vehicles in city centers and construction zones are growing and, especially in Europe, electrification is the next step.
A number of OEMs are already moving ahead on this front with battery-powered versions of existing machines. Almost all are first-generation, where electric motors and batteries basically replace the engine. At this phase of electrification, for the most part it’s still about powering existing hydraulics. Next-generation machines, however, may bring modifications such as electric drives replacing hydraulic rotary drives on excavators, hydraulic wheel motors and, possibly, some linear actuators.
Beyond the sustainability effort, small electric equipment are already being used for indoor demolition and basement projects, in tunneling construction, and as low-noise machines required for night-time work and in quiet zones such as hospitals and schools. Here’s a look at some concepts and production models that have been recently introduced.
Volvo Construction Equipment has unveiled two zero-emissions machines, the ECR25 excavator and L25 wheel loader. The models, the first in a new electric range of Volvo-branded compact equipment, deliver no exhaust emissions, significantly lower noise levels, reduced energy costs, improved efficiency and less maintenance requirements, compared to their conventional counterparts.
To make the ECR25 and L25 electric, the combustion engines have been replaced. The ECR25 is fitted with lithium-ion batteries and one electric motor which power the hydraulics that move the machine and attachments. The L25 incorporates two dedicated electric motors, one for the drivetrain and one for the hydraulics. Decoupling the subsystems has led to higher efficiency in both circuits and in the entire machine.
The machine’s batteries store enough energy to power the ECR25 and L25 for eight-hour shifts in common applications, such as utility work and light infrastructure and agriculture tasks. Onboard chargers enable overnight charging via a regular household plug socket. A fast-charging option, requiring more powerful grid access, will also be offered.
The machines will be available for sale from mid-2020, when Volvo CE will begin to launch its range of electric compact machines and halt new diesel-engine-based development of these models.
Bobcat recently launched what it says is the world’s first 1-ton electric mini-excavator. Combining zero emissions, low noise and a width of just 28 in., the battery-powered, zero tail swing (ZTS) E10e can easily pass through standard doors and in and out of lifts.
The E10e is based on the diesel-powered E10 ZTS mini-excavator, with the same profile, identical external dimensions, and equal or better performance. The electrohydraulic powertrain system fully uses the electric motor capabilities. It is equipped with auxiliary lines and an efficient oil cooler system for continuous hydraulic breaker operation. The machine also accommodates hydraulic pilot-pressure controlled joysticks. And it offers extremely quiet operation on site at only 71 dBA vs. 80 dBA for the standard E10.
The E10e has a state-of-the-art lithium-ion, maintenance-free battery pack with a power-management system. Coupling the machine to an optional external Bobcat supercharger while operators are on normal work breaks lets the E10e operate for a full working day; or it can continuously work for four hours on a single charge in typical applications.
Wacker Neuson’s range of electric machines includes several wheel loaders, excavators, track and wheel dumpers, rammers and compactors. According to the company, it’s now possible to operate an entire construction site free of emissions.
For instance, the DW15e articulated electric wheel dumper with 4-wheel drive has a payload of 1.5 tons. It has one electric motor for the drive system and another for the work hydraulics, to operate functions independently and minimize energy consumption. When braking or driving downhill, energy is regenerated and, therefore, not wasted as heat but fed back to charge the battery.
The EZ17e zero tail mini-excavator provides a battery-operated counterpart to the conventional EZ17 excavator. The electric drive powers a load-sensing hydraulic system (LUVD) that offers smooth operation and excellent performance when using multiple functions at operating pressure to about 3,500 psi.
Its lithium-ion battery can be charged at a household socket or at a mains power connection (express charging process), which increases the machine’s running time over an entire workday. The machine also maintains its weight class, inclusive of the battery, and can thus be transported on a car trailer. Production of the EZ17e began in late 2019.
This past September at BICES 2019 in Beijing, LiuGong introduced three battery electric vehicles (BEVs), the 906E-EV and 922F-EV excavators and 856H-EV wheel loader. They use proven lithium-ion battery systems that power permanent-magnet motors to drive machine actions. Mechanical and hydraulic systems have reportedly been optimized for high efficiency.
The 906E-EV and 922F-EV excavators, for the most part, use the same hydraulic systems as does their diesel counterpart. The 856H-EV has a pure electric driveline with regeneration. This improves operating performance and reduces energy consumption. The hydraulic system is electrically driven using standard components.
The BEVs reportedly have peak power output double that of a conventional machine. This lets the electric earthmovers accelerate and work faster, and increase productivity by 10% compared to that of diesel versions.
Batteries are designed to last the life of the machine and the electric systems eliminate daily maintenance and regular service of the engine, saving time, materials and money. The first-generation BEV batteries are equipped with fast-charging technology, which need only one hour to charge the battery to 80% full and maintain uptime.
All three models are designed based on a common platform among parts and systems. This simplification will help lower the total cost of ownership. Officials said total operating cost of a battery-powered earthmover is, or soon will be, lower than that of a diesel-powered machine, depending on the customer application.
Mecalac’s e12 is the electric version of the company’s 12MTX excavator. With diesels slated to be banned from certain construction zones, it’s designed for urban building sites that are ever-more compact, high-performance and environmentally friendly. An articulated chassis lets it move easily around obstacles and terrain.
The e12 incorporates iron-phosphate (LiFePO4) battery technology that offers three times as many lifetime charge cycles as classic batteries, reportedly with complete safety — the components pose no risk of fires or fluid leaks. Moreover, the batteries offer a capacity of 146 kWh, which results in an unrivalled range of eight hours even in demanding conditions, and eight hours to recharge.
It has two independent electric motors powering the two main hydraulic circuits, one for operating excavation functions and one for travel. The electric transmission is said to offer best-in-class tractive force and brake-energy regeneration.
The 19C-1E is JCB’s first fully electric mini-excavator offered in North America. It is part of the company’s E-TEC family, a new generation of electric products with zero exhaust emissions, greatly reduced noise and no compromise on performance.
The 2-ton model offers the same power and more torque versus comparable diesel-powered machines. And at 7 dBA lower, it generates one-fifth the noise of its diesel counterpart. Eliminating the engine also substantially reduces vibration, improving the operator environment.
The 19C-1E includes a Bosch Rexroth load-sensing hydraulic system for excellent digging performance and bucket tear-out. The high efficiency electric-hydraulic system also lowers cooling requirements — only a small hydraulic cooler with a thermostatic electric fan and no engine radiator are needed — and contributes to longer battery life and less noise.
Three lithium-ion batteries store 15 kWh of capacity, enough to power through a typical workday on a single charge. An optional four-battery pack increases capacity to 20 kWh and delivers an additional two hours of continuous use. Recharge time with standard 110 V input is 12 hr; available 230-V option is 8 hr; and the fast-charge option gives a 2-hr recharge.
JCB research indicates that electric charging costs for the 19C-1E will be 50% lower than fuel costs for a comparable diesel-powered machine over a five-year ownership period. Similarly, with fewer consumable spare parts and fluids, servicing costs could be 70% lower.
Cummins and Hyundai Construction Equipment have jointly developed an electric-powered mini-excavator. The collaboration reportedly combines the strengths of Hyundai CE’s versatile excavator design with Cummins’ lithium-ion battery technology and machine integration expertise.
Powered by Cummins BM4.4E flexible battery modules (4.4 kWh each), the 3.5-ton excavator is designed to operate for a full eight-hour shift and charge in under three hours. The machine eliminates all gaseous and particulate emissions and substantially reduces noise, making it ideal for use in urban and suburban construction.
The excavator contains eight BM4.4E modules connected in series to provide a total storage capacity of 35.2 kWh. Mounted in the base of the excavator, the modules combine high energy density and proprietary control technology to maintain the battery state-of-charge for a longer operating range. A modular design lets the system be built up and aligned to the duty cycle of the excavator.
The goal is to design electrified products that match or exceed the reliability and performance of their diesel counterparts. The prototype machine is being tested to optimize performance, prove the structural integrity and enhance marketability.
Kobelco displayed a 1.7-ton electric mini-excavator concept at last year’s bauma exhibition. The unit builds on previous developments in hybrid and electric technologies, such as the iNDr (Integrated Noise and Dust Reduction Cooling System) and innovative high-efficiency hydraulic systems.
The 17SR unit reportedly combines Kobelco’s expertise in developing efficient construction machinery for urban jobsites with Deutz’s electric-drive technology. The objective is to manufacture a fully-electric mini excavator that will perform at the top of its class and deliver zero emissions, extremely low noise operation, reduced life-cycle costs and long battery life.
Kobelco expects to launch the 17SR in 2021. The company’s long-term objective is to further expand its machinery line-up to include more electric-driven excavators and help promote a sustainable society.
Komatsu has demonstrated an electric-motor/lithium-ion powered mini-excavator that mirrors a diesel-based PC30MR-5 machine. The design is based on existing Komatsu fork-lift and hybrid technology, the only difference is that the hydraulics are driven by electric motors.
The circuits include two variable-displacement piston pumps producing 18.3 gpm for boom, arm, bucket and travel operations; and two gear pumps for swing and blade functions with flows up to 5 gpm. The systems are rated in the 3,000 psi range. Variable-displacement piston motors are integral for the hydrostatic travel drive, and fixed-displacement piston motors for swing.
With a power rating of 18.5 kW, the machine has the same rating as the diesel version. Performance is the same in terms of digging power and speed, and it operates virtually without discernable noise. However, it does have better stability as it weighs a bit more.
In light to medium-duty application conditions it will work for up to six hours. In extreme conditions, it may need recharging in as little as 2.5 hours. With standard power, it recharges overnight; a fast-charging system permits recharging in an hour. The prototype machine is currently on test at customer sites in Japan.
Kubota’s KC70-4e electric mini-crawler dumper reportedly matches the performance of similar machines that run on diesel, but lets users work in settings where emissions or noise levels may restrict equipment. The KC70-4e is equipped with a 4.8 kWh lithium battery and has a payload capacity of 1,550 lb.
The transmission in this machine has been changed from hydraulic to electric, with two CTE2010 motors that operate at 48 V. With a width of 30 in., the electric mini-dumper has a robust and consolidated lower frame that makes the machine easy to maneuver, permitting operational ease across a range of jobs and settings. The KC70-4e will be available in select markets in early 2020.
Filed Under: Mobile Hydraulic Tips