​Keestrack's latest jaw and cone crushers provide full electric processing

Five end products with a production capacity of 180 t/h and total diesel consumption of 60 litres per hour – those were the impressive key results of a multi-stage crushing and screening combination demo of four mobile Keestrack plants, first publically tested in autumn, 2016. The tests were conducted during the customer days of Norway-based Keestrack dealer Fredheim Maskin, and formed part of a technical premiere for Keestrack's “full-hybrid” drive technology. Debuting as a full-electric combination powered by an external gen set were Keestrack's all-new jaw crusher B4e and the mobile cone H4e – both with new drive systems, using diesel power only when needed.

Using Fredheim's Demo Days as platform to present its new full-hybrids was well planned by Keestrack. With over 40 plant exhibits of several brands, the event in Spydeberg, Norway, some 30 km south-east of Oslo, exceeds the expectations of a normal “in-house” show, according to Keestrack, attracting specialist visitors from all over Scandinavia and other international markets. With a record of 650 Keestrack plants sold in Norway and Sweden since 2005, Fredheim, led by the brothers Per Olav and Svein Fredheim, is one of the most successful Keestrack global distributors – reflected by the 2016 “Dealer-of the-year” award, presented for the eighth time to Fredheim.

Highlighted at the Fredheim machine demonstration, along with over 20 plants working in a granite quarry, was the Keestrack's full-electric tracked processing line including the B4e jaw crusher with stacker S5e (for 0/20 pre-screen), the H4e cone with 3-deck-afterscreen module and the final 2-deck-classifier K3e which produces five end product fractions. With a feed size of 600 mm and different sets of end products, including double crushed chippings (0/2 … 16/22; 0/4 … 16/22), the combination of machines reached a maximum production of 180 t/h. Without activating their onboard-diesel engines, all machines were powered through a single 500-kVA external gen set. Consumption analyses over several days gave average values of under 60 litres per hour fuel usage.

"We were surprised by these results,” states Keestrack president Kees Hoogendoorn. “Even if these values are quite specific, they clearly reflect the high economic potential of our full-hybrid technology. Applied in a mobile multi-stage processing line, as presented here for the first time, it offers great advantages for the contractor. Not only in daily practice, but specifically in long-term evaluation if we consider lower maintenance costs and longer service life.” 

Long experience

Keestrack's new "Full-hybrids” include the early introduction of modern load-sensing systems in diesel hydraulic drives and the partial electrification of crushing and screening plants through the wide use of electric motors on conveyors and separator components. “Every new level in development brought important savings in diesel consumption,” explains Kees Hoogendoorn, referring to the 20 – 30 % improvement they have seen, made through modern hydraulics, diesel-electric components and external “plug-in” operation, which is today available throughout all Keestrack plant technologies. “With their substantially smaller hydraulic circuits our hybrid systems provide advantages in maintenance, availability and safety – especially when working in environmentally sensitive areas.”

While the screeners and conveyors on hybrid Keestrack classifiers and stackers are operated electrically – the diesel driven hydraulics only supplies hydraulic cylinders and crawlers – all Keestrack crushing units were up to now only powered directly through the on-board diesel engine. “Electric drives supplied via external gen sets or mains certainly offer high saving potential, but without compromising the plants’ mobility, crushing performance and productivity, which depends also on optional modules with high power demands,” said Hoogendoorn.

"Zero-emission" crushing

As a result of changing technologies Keestrack presented, at Bauma 2016, the track mobile cone crusher H4 with 345 kW/330 KVA diesel/generator module, 132 kW electric drive for the crusher and extensively electrified conveyors and screening components. Despite its comprehensive equipment, including an optional 3-deck after-screen with oversize conveyor, the compact, transport friendly plant, weighs only 46 tonnes and can be operated as “plug-in”. At the recent demo in Norway, Keestrack presented the full-hybrid model H4e, featuring an additional electric motor/hydro pump unit to supply all installed hydraulic functions (feeder, hydraulic cylinders, tracks) via external current without starting the diesel engine.

The all-new Keestrack B4/B4e jaw crusher is optionally available with conventional diesel-hydraulic drive or as full-hybrid “e-version”. With active 2-deck pre-screening and the re-designed 1100x700 mm jaw crusher featuring the patented N.S.S. overload protection. The new model follows on the successful Apollo/B4 for flexible recycling applications or medium-sized quarry operations with capacities up to 300 t/h. Completely equipped with new options, like a 1-deck afterscreen module with oversize conveyor, the newly designed frame incorporating elements of high-strength Domex steel guarantees low transport weights (max. 49 tonnes). The full-hybrid Keestrack B4e is equipped with a 242 kW diesel engine and a 225kVA on-board generator. The latter supplies the 110 kW electric crusher motor, all other electric drives on conveyors and screens and the separate 55 kW electric motor/hydro pump unit for all installed hydro drives (cylinders, tracks). During “plug-in” operation (external gen set/mains) the diesel engine doesn’t have to be started, and complete energy management is controlled automatically, including the electric supply of a secondary unit (screen or stacker).