Getting It Right
April 6, 2005 • Although it can't be compared to the US-Soviet arms race of the 1960s and 1970s, there's little doubt that Genie Industries, Redmond, Wash., and rival JLG Industries are in a race all their own.
Image 1: The new Z-135/70 from Genie boasts 135-foot platform height.
As one company introduces a new product, it's not long before the other manufacturer responds in kind. The new Genie Z-135/70 articulating boom lift is a direct response to the highly successful Ultra-Boom™ series introduced by JLG,
In the making
Genie's management set two specific requirements for the development of the 135-foot Z-135/70. The first was to build the tallest machine possible that could be legally transported on a standard single-drop trailer, the kind most commonly used by rental operators. Second, senior management made it very clear that the design needed to be right the first time. To accomplish this Genie undertook the most expensive and rigorous product development protocol in the company's history.
Two prototypes, built to ensure the transfer of engineering drawings and concepts to a material product, got the project started in 2003. Combined, the boom assemblies of these prototypes underwent more than 90,000 lift cycles. That equates to more than 20 years of use. Since then, no less than eight pre-production machines have been put through a myriad of real-world tests, allowing further refinement, while providing direction for the efficient production of the units.
The end result is an articulating boom lift with 135-foot maximum platform height and 69'9” of maximum horizontal reach that weighs an impressive 44,900 pounds. As if these specifications aren't enough to impress, I was wowed by the up-and-over height numbers. At 75 feet, the boom can reach almost 60 feet from the centerline of rotation. Additionally, the 8-foot long steel platform accommodates unrestricted, 600 pounds of load.
Of course, gross vehicle weight is not the only transportation issue to be addressed. Overall stowed length and width on the Z-135/70 is 42'5” and 8'1”, respectively. Stowed height is a low 10'1”, and when the boom is in the stowed position, the leading edge of the pivot assembly offers 51 inches of clearance. This is more than enough clearance for rolling onto a drop deck trailer and provides an excellent approach angle when climbing an incline. Its stowed dimensions are driven by European transportation standards requiring 2.5 meter width, while the 12'11” extended configuration facilitates stability for operation.
Expanding axles
While its reach capabilities are certainly striking, what really sets theZ-135/70 apart from other “mega” booms, is its patented X-Chassis expanding axle design. Image 2: X-Chassis axles are shown in the stowed position for transporting.
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Competitive models and Genie's other 80-foot-plus units incorporate extending axles that utilize a sliding box within a box telescoping design. Genie, however, has developed a system that independently mounts each axle on vertical king pins. The simple four-bar linkage geometry utilized to achieve this configuration is not revolutionary, but it is unique in this application.
Image 3: Here, axles are in the operational position.
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As the machine is driven in either forward or reverse, the operator depresses a button on the upper control console to activate a set of hydraulic cylinders; these cylinders fold the axles in or out. Key to this design are Hall effect rotary sensors. Originally utilized to eliminate the need for tie rods in extending axle machines, Genie has taken their capabilities a step further. These non-mechanical sensors monitor the axles' pivot positions, thereby controlling the steering geometry and also the four steering modes (2-wheel front, 2-wheel rear, 4-wheel and crab). Working in partnership with each other, the axle sensors keep the axles in proper alignment with the wheels no matter what the position.
The folding axles are made of high-strength steel castings, an expensive option I was told, but essential considering the perceived benefits. Eliminating the telescoping tubes reduces the number of moving parts, the need for slide pads, and the need to internally capture and manage the hydraulic hoses that ride in and out with the axles' movement. It is easy to see why Genie expects modest wear as the hose is only asked to bend minimally. This is just one of several design decisions Genie has made in order to reduce wear or improve accessibility for service.
Image 4: Hydraulic valves have been moved from the superstructure to a location on the chassis for improved accessibility.
In a departure from most other RT boom lifts, Genie has decided to locate many of the hydraulic control components and drive and steer manifolds on the chassis. Moving these access points to lower locations has distinct service benefits.
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Image 5: All service points on the Cummins engine are located outboard.
My test unit was fitted with a Cummins B4.5 L diesel producing 80 hp. Perkins 1104C-44 - 86 hp or Deutz BF4L-2011 - 78 hp engines are also no-charge options. All three engine choices come on a 50° swing-out service mount. Notice that all service points on the Cummins engine are mounted outboard, indicating that it is unlikely that this engine will have to be swung out for service. Note the thermostatically controlled, hydraulically driven oil-cooling fan in Image 5.
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To facilitate replacement or inspection hydraulic hoses and electric cables have been bulk-headed at the top and bottom of the upper boom assembly. Quick disconnects are provided to expedite this procedure.
In Part Two, I will delve deeper into the Z-135/70's boom assembly and various system designs. Plus I will give you my first-hand impression of operating this new Mega boomlift.
