Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/917937
December 2017 | EquipmentWorld.com 22 Operator comfort Tom Connor, excavator product spe- cialist with Bobcat, says cab size suf- fered when zero- and reduced-tailswing became driving forces in compact excavators. The industry is working to bring back roomier cabs. Even an inch matters, he says, especially with such details as foot room and joystick placement. With the larger cab, Bobcat has been able to use the same seat in compact excavators as in their skid steer and compact track loaders to increase operator comfort. Connor says the simpler emissions hardware of sub-75-horsepower engines takes up less space, making it easier to include larger cabs than if a selective catalytic reduction (SCR) system were in place. Another space-saving design in Bobcat compact excavators are the hydraulic reservoirs, which are one-third the size of those on most competitors' machines, according to Connor. Where large reservoirs are often used to help control oil temperature, "there's no need for a surplus of oil with Bobcat's high- performance cooling packages," he says. Noise reduction is another component of operator comfort. One method of reducing noise is to create a quiet cab. Another is to reduce noise emitted from the source. Kobelco compact excavators from the SK17SR to the SK55SR feature the company's Integrated Noise and Dust Reduction Cooling System (iNDr). The system uses a tightly sealed engine compartment, offset ducts and a muffler designed to slow and disperse exhaust for quieter operation. Hydraulics Hydraulic systems and the electron- ics that control them have become far more efficient and powerful in recent years. Load-sensing hydraulics is one such example. Machine electronics al- locate hydraulic resources based on the task being performed. Complementing the load-sensing hydraulics on many machines is an advanced hydraulic re- generation circuit. With regeneration, oil from the rod side is retained in the cir- cuit rather than routed back to the tank Features to enhance operator comfort on the Cat 303E CR include an adjustable suspension seat, retractable seatbelt and adjustable wrist rests. The joystick and travel levers are ergonomically designed to reduce fatigue and improve pro- ductivity. With the Cat Interlock System's hydraulic lockout lever in the up position, no operational function is possible, including travel. The Hitachi ZX30U-5 is powered by a Yanmar diesel rated at 23 net horsepower and meets Tier 4 Final emissions stan- dards. Auxiliary hydraulic lines run to the end of the boom; quick couplers are optional. Maximum travel speeds with the two-speed drive are 1.7 mph in low and 2.7 mph in high. M ike Watt, excavator product manager for LiuGong, says the two models currently avail- able, the 906D and 908D, are Tier 3 machines due to be withdrawn from the North American market. In the wings are the 908E, a Tier 4 Final reduced-ra- dius machine that should roll out in the second quarter of 2018. Produc- tion is getting underway in Changzhou, China, with new engineering and a new production facility. The Tier 4 Final, 4.1-metric-ton 9035E was unveiled at the November 2016 dealers meeting and displayed at the 2017 ConExpo. It's undergo- ing final field testing at a dealership in North Carolina. LiuGong on the horizon machine matters | continued