Packaged for the Rental Market (Part 2)
September 15, 2004
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Image 1: Grove's new RT890E will soon be joined by a 75-ton RT875E.
To learn more about how the RT890E's design was influenced by market demand go to Part One 
The RT890E features an impressive drive train. It is powered by a Cummins QSB turbo-charged diesel engine. The 6 cylinder, 5.9 liter engine produces 275 hp (205 kW). A Clark HR-32000 series power shift transmission is equipped with an integral torque converter. The transmission drives a set of limited-slip axles supplied by AxleTech International,
While Cummins makes great engines, in my estimation, one common complaint about them is how loud they are. The engine in the RT890E was no different. Even at idle, I had to shut the crane down in order to communicate with anyone standing just below the cab entrance.
Boom design
The RT890E uses Grove's Megaform boom design, carried over from the GMK all-terrain crane product line. This boom features a curved or nested bottom which improves rigidity.
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Image 2: Two string potentiometers assist with boom sequencing.
The five-section boom telescopes from 38 to 142 feet with a 150-foot maximum tip height. All telescoping functions are controlled by the PAT-supplied load indicator system, which keeps the boom sequencing in proper balance. This requires the use of two individual string potentiometers.
Three boom operational modes are available, but only two are pertinent to the operators. In the most commonly used operational mode, B Mode, the inner mid-section of the boom can be extended 75%. Then the PAT system switches to the opposite extension cylinder to allow the center mid-section to be extended 75%. The system then finishes extending the first section and finally completes extension of the second section. Once fully deployed, a combination of chains and cables extend the outer mid- and tip-sections in unison.
An optional manual jib offsets at 0°, 20°, and 40°. The 33- to 56-foot hydraulic bi-fold and swing-away jib, also optional, offsets to a maximum of 40°. Charts for the hydraulic jib are included in the LMI system. Two 16-foot lattice inserts can also be added. Combined with the 56-foot jib, maximum tip height is an impressive 236 feet. Compared to previous generations, this is 43 feet more tip height than the RT875C and 32 more feet than the RT865BXL.
From the cab
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Image 3: The E series cab features the i-Flex 5 LMI system from PAT America.
Featuring the E series cab, controls are well-placed and easily identified. On the right side of the dash is the i-Flex 5 LMI screen supplied by PAT America, Germantown, Md. This is PAT's most advanced system featuring a full graphic display. Thanks to its back lighting and automatic internal brightness adjustment I had no trouble reading the display even in the bright sunlight. This system also features a Work Area Definition function that allows the operator to pre-select and define safe working areas. A2B is standard.
Settling into the cab, I was surprised that the six-way adjustable seat did not have a suspension. That's not a lot to ask for a piece of equipment with this kind a price tag. Although I have no previous experience operating a Grove crane, it took only a matter of minutes to feel in control of all functions. I found the controls to be intuitive; joystick movement and pump speed to be well-blended, delivering predictable response; and controls were well-placed for the potential to reduce physical and mental fatigue. The highly detailed, yet concise, load chart and operator manual are located in a binder and conveniently stored over the operator's right shoulder.
Primary winch control is located on the right and the test unit I operated included the auxiliary winch with controls on the left. These are single-axis joysticks. (European units are fitted with dual axis joysticks.)
Foot pedals (see Image 3) control engine throttle (on the far right); drive brakes (second from the right); slewing brakes (on the far left), and boom telescope (second from the left). Additionally, a hand throttle permits the right foot to wander to other functions thus facilitating multiple foot-controlled operations.
Simultaneous operation of swing, telescope, lift, and hoist was no problem for the massive amount of flow produced by the Parker pump. Operators can choose between high and low swing speeds with a maximum rotation speed of 2 rpm. Operation was smooth and the swing brake brought the boom to a silky stop. I can't imagine how smooth operation would have been in the hands of a pro. The only hitch I experienced was a slight surge during boom extension. Grove was forthright about some minor issues they were having with that and informed me that they are currently working through the issue related to the pilot-operated control valves with Parker. Electric over hydraulic valves might solve the problem and is a solution Grove is considering.
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Image 4: The cab tilts 20° putting the operator in a comfortable position to sight the load.
I appreciated the excellent field of vision the cab afforded. Skyward view was unobstructed and enhanced by standard 20° hydraulic tilt cab. Operators will appreciate the comfort and safety the tilt cab provides.
Single-stage double box beam outriggers can be set in three positions—stowed, 50% and 100% extension. Leveling is left to the operator with only a simple, yet effective, bubble gauge to support the process. Deploying and then stowing the outriggers took a matter of moments.
My only real concern was limited visibility to the right rear of the machine. Although a side mirror gave me clear line of sight to the right rear outrigger, I wasn't sure when the outrigger was fully retracted. The small mirror was far enough away from me that it was difficult for my corrected vision to make out the object in the mirror. Maybe I needed to clean my lenses.
To prevent inadvertent operation of the outrigger controls this is a two handed procedure. One hand is required to activate the enabler while the other hand controls the function.
Operational impressions
There are six forward and six reverse speed drive selections, accomplished by splitting the three-speed transmission into a high and low range. The high speed range is achieved by disconnecting the front axle and throwing maximum flow to the rear axle. When traveling with the boom raised about 15° my field of vision was superb. Although imperceptible by the operator, the rear axle oscillates up to 10 inches when the boom is carried over the front center of the chassis.
Machine bounce is unavoidable in a rigid-framed machine of this size. But the massive air-filled 29.5 - 25 General bias ply tires did a good job of flexing their sidewalls to minimize bounce as I approached top speed of 22 mph.
A momentary switch actuates, on the fly, rear axle control for crab, rear wheel or four-wheel steering. A dash mounted light indicates when the wheels are properly returned to the centered travel position. Power steering was responsive with just enough resistance to avoid over steer.
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Image 5: Cab is equipped with both a sliding roof and retractable sun shade.
On a nice day you can you can slide the top and right side glass windows open and a retractable sun shade helps keep the sun off the operator's brow. To top it off, the cab features an optional air conditioner, which is ordered on nearly 90% of all Grove RT cranes. This makes my request for a suspension seat seem even less extravagant.
All in order
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Image 6: CanBus interface (see arrow) is grouped with master electrical disconnect and hour meter.
Inspection and service of the RT890E seems straight forward—an important aspect for a piece of equipment that must be checked over daily. To access the engine and to check crank case oil levels the superstructure must be rotated 90°. The Cummins engine features a Can-Bus computer interface for engine diagnostics. Ports are located inside the cab and on the outside of the structure. The external port is located to the right of the hydraulic oil cooler radiator. Also located here is a master disable switch. All filters are accessed from the ground.
Front and rear fenders are flat and aluminum diamond plate bridges the fenders from front to rear resulting in a massive deck from which service, inspection, and cleaning can be performed. Four ladders provide access the deck.
A base machine with all the standard features we mentioned is priced at $676,050, while popular options like offset jibs and the auxiliary hoist are available a-la-cart. Grove offers special value marketing packages, however, that include some of these popular items. For example, for $56,050 you can get a package that includes the manual jib, auxiliary hoist, and 360° NYC-style swing lock. Initially required in the city of New York, an NYC lock is a manual swing (slew) lock that is now required in other locations.
Likes
· Machine dimensions and weight make the RT890E easy to transport.
· Well-positioned, intuitive controls delivered smooth operation.
· Tilt cab affords excellent visibility for the operator.
· PAT's i-Flex 5 LMI provides the operator with good overall control of the crane.
Dislikes
· Cummins engine is too loud.
· Split winch controls might work better if both featured right handed operation.
· The power surge during boom extension needs tweaking.
Verdict
The RT890E offers an RT crane package sure to be appreciated by North American rental buyers as well as in markets worldwide.
