Compact in design and big on performance, Caterpillar’s comprehensive mini excavator range delivers across all industries, thanks to ‘smart iron technologies’.
In today’s market, Caterpillar designs and produces a wide spectrum of mini excavators that meet industry demand for compact machine performance in niche roles. Despite their size, these are powerful machines, at the cutting edge when it comes to multi-tasked delivery, either in compact radius (CR) configuration (optimal when working in confined spaces), or standard specification, coupled with their easy portability and simplified maintenance.
For the local market, southern African Cat dealer, Barloworld Equipment, supplies four key models: the Cat 301.7D (weighing in at approximately 1 610 kg with canopy, and well suited for internal building demolition tasks when equipped with a Cat hammer); the Cat 303.5E2 CR and Cat 305.5E2 CR, both popular industry choices for construction and plant hire; and the Cat 307E, which finds favour across the full industry spectrum.
Caterpillar first entered the mini excavator market back in 1998 during a boom period for cabling laying in Europe, with the research and development programme subsequently evolving over time. (The first models, the Cat 301.5 and 302.5 were assembled in Desford, UK.)
The Cat 301.7D, and the latest generation E2 series models launched during 2014 and 2015 are manufactured at Caterpillar’s facility in Athens, Georgia, USA, for worldwide distribution, whilst the Cat 307E is produced at Caterpillar’s Wujiang factory in China.
All models, with the exception of the 307E, come standard with rubber tracks, although steel tracks are available as an option (usually for tougher underfoot applications).
E2 EVOLUTION: COMPASS & HDH
“The Cat E2s carry on the solid performance of their E Series predecessors, while adding even greater value,” says Hugo van der Walt, product marketing manager: Building Construction Products (BCP) at Barloworld Equipment.
The Cat 303.5E2 CR and Cat 305.5E2 CR units are powered by Cat C1.7 and Cat C2.4 power plants generating a net power (ISO 9249) of 17.5 and 32.9 kW respectively.
“Key features to note as standard include their new High Definition Hydraulic (HDH) system; redesigned operator station; and their purpose designed COMPASS (Complete, Operation, Maintenance, Performance and Security System) digital control panel.”
Built into the COMPASS monitor are an anti-theft system, which requires a five-digit alphanumeric password to start the machine, an automatic engine-idle selection, which drops engine rpm to idle after four seconds of inactivity and an adjustable auxiliary-flow control for work tools. Both main-line and optional secondary auxiliary-hydraulic systems can be adjusted on a scale of 1-15 through the monitor for added control.
In turn, Caterpillar’s HDH system provides a load sensing and flow sharing capability leading to operational precision, efficient performance and greater controllability. The simple valve architecture reduces heat, which leads to a reduction in hydraulic instability and improved overall efficiency. On the Cat 303.3E2, the typical efficiency gain compared to the previous generation model is around 7%, with a fuel consumption improvement of some 8%.
Today’s strict health and safety environment is catered for with best-in-class ergonomics, which on E2 models features a redesigned operator station. This update includes a wider opening, a high quality suspension seat, easy to adjust arm rests, and a new interlocking front window system. Standard features retained include automatic two-speed, 100 percent pilot controls, superior bucket rotation and blade float function, which allows the operator to drag the blade backwards (away from the cutting edge side): in the process, the blade will “float” along the contour of the ground with only the weight of the blade bearing down to smooth the site after grading and backfilling holes.
The automatic two-speed feature allows the operator to put the machine in “high speed” (rabbit) and not worry about manually kicking down to low gear while turning, digging, or roading in tough conditions. One hundred percent pilot controls offer consistent and long-lasting controllability with reduced owning and operating costs compared to those often associated with mechanical linkage.
The unique design of the Cat linkage, bucket, and cylinders on the approximately 3 to 6 tonne operating weight units (e.g. the Cat 303.5E2 CR and Cat 305.5E2 CR at 3 723 and 5 423 kg respectively with cab fitted) allows for an industry leading 200 degrees of bucket rotation, comparable with the signature Cat backhoe loader excavator arm’s design functionality. This rotational ability allows for easier vertical wall digging without repositioning the machine, and greater material rotation during truck loading.
Their bucket shape also maximizes the volume of material per scoop without sacrificing digging performance and the boom and stick cylinders have built-in dampening to cushion the impact of the rod and piston against the stops when it reaches full extension or retraction.
The dig depth on the Cat 303.5E2 and Cat 305.5E2 is 2 880 and 3 470 mm respectively, and maximum reach 5 200 mm and 5 790 mm.
CAT 307E: A CLASS LEADER, WITH ‘FRONT SHOVEL’ OPTION
Sharing this legendary pedigree towards the top end of the Cat mini excavator line-up is the Cat 307E. The excavator weighs in at around 6 800 kg and comes equipped with the new Cat C2.6 DI turbo engine generating a gross output of 43 kW. This power plant is matched with the machine’s load sensing hydraulic system to provide excellent digging performance and precise operation in any application, from fine grading and dozing to backfilling.
Stick and bucket digging forces on the Cat 307E are class leading at 37 kN and 50 kN, respectively; whilst maximum reach at ground level is 6 300 mm, with a digging depth to 4 100 mm and dump height to 5 150 mm. The standard bucket size is 0,31 m³.
Caterpillar’s Cat 307E can also be configured as a ‘front shovel’ by turning the bucket around for optimum flexibility. On-site tasks here include utility pipe services, backfilling along walls, and cleaning material from inside truck beds.
Standard features on units sold into the southern African market include air-conditioning; 2 speed travel mode; hydraulic lines for various Cat work tool attachments, such as hammers and augers; and a push blade with blade float function.
On the move, travel is via the machine’s standard 450 mm triple grouser steel tracks, which provide optimum stability, particularly when lifting over the side in demolition and heavy duty applications. Each track is driven by one independent two-speed motor. (Drive modules are integrated into the roller frame for total protection.)
Finally, all Cat mini excavators from 3.5 to 8 tonnes are ROPS, FOPS and Top Guard Level 1 certified; include the Cat Interlock (hydraulic lockout) System – a certified accumulator which allows for auxiliary pressure to be released. This makes connecting and disconnecting work tools safer and easier.
“Caterpillar’s research and development team continue to raise the bar on mini excavators in key areas like hydraulics, which have revolutionised the return on investment owners can expect from a compact machine,” adds van der Walt.