Masonry Magazine February 1993 Page. 18
Just the Facts
An examination of two basic rough terrain forklift boom systems-fixed boom and sliding boom types.
By JAMES E. HOOGERVORST
National Salesmanager
Lull Corporation
USING ONE lever to move the forks of a rough terrain forklift in a horizontal plane at any boom angle can be done mechanically, electrically/hydraulically, hydraulically/hydraulically and manually. There's little doubt that such systems make running a machine much easier. The operator only has to position the load in front of the landing area and then gently move the load, using.
Fixed Boom Type
As with all fixed boom machines, the landing height is about 4' less than the maximum lifting height, (Figure 1). The usable height of the system is also 4' less than maximum lifting height because of the need to withdraw the forks from the load.
All the systems must keep a constant account of: (a) boom angle, (b) boom extension, and (c) machine angle to level.
When the system is activated, the flow of oil is automatically proportioned to the boom extend and boom lower to make the forks go horizontally forward. Through each degree of boom angle the proportion of oil is changed to each function.
When withdrawing the forks, the opposite functions of boom raise and boom retract are activated with the proportion of oil changing as the boom angle is increased.
Whether the machine used a computer chip, oil flow divider valves, electronic sensing, or hydraulic displacement, the system is complex and requires technical service. It is notable to remark that the advertisements contend that the machine will perform normally if the systems fail to operate for any reason. Jobsite feedback tells of problems encountered with computer reliability, boom angle and boom extension sensor failure, oil displacement monitoring problems due to ambient temperature changes, and various complaints.
Already, two manufactures have stopped offering the computerized version due to excessive warranty and maintenance experience.
Sliding Boom Type
This system allows the boom to move forward and rearward on the chassis of the machine at any boom angle. (Figure 2). Since the lifting cylinders move with the boom, the capacity of the booms lifting ability remains the same.
The sliding motion of the boom, called "Transverse", acts as a boom section in that it offers either 72" or 80" of additional forward reach at all fork elevations. Two sections of boom along with "Transverse" will exceed the capabilities of most three section boom machines.
Landing height of the sliding boom machines is the same as the maximum lifting height because the forks can travel forward 72" or 80" without lowering the boom. This allows the machine to place material while sitting farther away from the landing site. Four steel rollers and a hydraulic cylinder operate the transverse system with little or no maintenance. First offered in 1962, "Transverse" has been time proven for thirty years.
When precision placement is required at high elevations, many features contribute to a machine's smooth operation:
Roller Boom eliminates chatter and jamming found in slide type