Getting from yard to job site.
By Phillip Cutler, P.E.
Either you have determined what products you will make or have put considerable thought into it. You have researched everything from aggregate storage to batch plants to forms to lifting equipment and everything in between. But you also have to deliver your product to the customer.
How will you get your products from your plant to the job site? What type of delivery vehicle should you consider for your particular product? As with all other equipment you’ll need as a precaster, the choices are many. Now you’ll need to become familiar with terminology such as lifting capacity, turning radius, reach, boom, knuckle boom, A-frame and flatbed to name a few.
Before you buy your first delivery vehicle, you’ll need to figure out how to get the product on the truck. A forklift is the most popular means of accomplishing this task. What do you consider when looking for a forklift, and why would you choose to load with a forklift?
A forklift is relatively small and maneuverable compared with the larger footprint of a mobile gantry crane or truck-mounted lifting system. It’s all about the choices. If your yard has limited space for product storage or your plant has narrow aisles in the production area, you might choose a forklift for this very reason. The size and weight of your products will definitely impact your decision on the size of forklift you might choose.
Forklifts can be set up with specialized equipment that hydraulically clamps and rotates products in place of the standard forks. They can also be equipped with devices that lift and carry multiple pieces from the yard to your delivery vehicle. For example, if your product mix covers a range of different-sized pipe, manhole risers, cones and bases, a forklift fitted with the appropriate attachments helps make quick work of moving, stacking, handling and loading these types of products.
Forklifts come in all sizes ranging in capacity from just a few thousand pounds up to 35 tons. Some are equipped with a solid or cushion-type tire, while others may have dual pneumatic tires or special all-terrain tires. For in-plant use and in closed, very tight spaces, electric models are available. These models tend to be smaller in size with extremely short turning radii and lifting capacities through approximately 6,000 pounds. Many have very limited or specialized uses for precast facilities. Larger models come with a choice of gas/lpg (liquid petroleum) or diesel power plants and handle heavier products. Structures such as utility vaults, traffic barriers, on-site wastewater and pump tanks, large manhole and multiple pipe sections, and flat slabs are handled with relative ease.
Whether your facility is level and paved or has a gravel base, a forklift can be a very useful, versatile and productive piece of equipment for moving and loading your products for shipment, depending upon your specific needs. If you are considering a forklift for your operation, consult with NPCA associates and suppliers of these vehicles and equipment. A talk with the experts will help you determine the best lifting solution for your needs.
The size of your products and their delivery locations play important roles in the choices you will make in delivery equipment. There are many aspects and variables that make up the specifications of the optimal delivery vehicle, so for a given set of application criteria, it is impractical to state that one solution is better than another. However, choices need to be made regarding the truck that best fits your operation and the work that you do. Will your truck be a pickup, a van, a flatbed, a custom chassis or a tractor-trailer rig? Do you need a light-duty, medium-duty or a heavy-duty truck? You may have needs for all three sizes.
If your products are relatively lightweight and the delivery site has weight restrictions or you must maneuver into very tight places, you might choose a pickup or van pulling a small trailer to deliver and install your product.
A light-duty truck is a Class 1 to Class 3 rating or a vehicle with a GVW (gross vehicle weight) of up to 14,000 pounds. More commonly known as a 1 / 2-ton, 3 / 4-ton or 1-ton pickup, cab and chassis, flatbed or van chassis, these vehicles are available right from your local auto/truck dealer or fleet provider with gas or diesel engines and a limited number of automatic and manual transmission options.
A limited number of options makes decisions relatively easy with Class 1 to Class 3 equipment. They are used effectively to transport you, possibly other personnel, and installation and support components to your job site. Light-duty vehicles are not usually fit with specialty equipment beyond a light-duty rear power lift, a bucket or plow, and they do not transport payloads beyond 6,000 pounds.
Once we leave Class 1-3, vehicles become increasingly sophisticated in terms of available options. The engine, transmission and chassis choices and the number and styles of axles that can be packaged for your particular delivery requirements seem endless.
A medium-duty truck chassis fits into the Class 4 to Class 6 designations. Vehicles in this range normally have a rated GVW of between 14,000 and 26,000 pounds. However, this rating can be stretched somewhat and push toward the 30,000 GVW level, depending upon your specific equipment and options chosen. Some medium-duty trucks are available directly from a fleet dealer’s stock or they may be purchased as a special order depending on the specific configuration you require.
Vehicles in Class 4 to Class 6 are capable of payloads up to 15,000 pounds in single-axle versions and beyond this limit with the addition of an optional air-lift or ‘air-tag’ (air-actuated, non driven axle set to support an increase in payload capacity). These mid-range machines offer a great deal of flexibility and can easily be fitted for use with booms, cranes, drop beds and in flatbed versions.
In the truck world, once we hit the heavy-duty or Class 7 and Class 8 ratings, the sky is the limit on the available configurations and options. Class 7 and Class 8 chassis are rated at GVWs over 26,000 pounds. These rigs are configured for heavyweight applications with payloads of 25,000 pounds and beyond.
Engine, transmission and drive train options are also nearly unlimited, depending upon the terrain and duty your application dictates. You can choose from a number of diesel power offerings from 325 to a monster 500 horsepower-plus option. Automatic transmissions are available, as well as the familiar nine-speed, 10-speed and 13-speed models. If delivery requirements take you off-road regularly, these models can be built with a heavy-duty transfer case, offering multiwheel or all-wheel drive configurations. Class 7-8 vehicles are usually considered semi tractors or tri-axle dump trucks. Although this is true, these conventional cabs (driver’s cab behind the front axle) and cabover (cab positioned over the front axle) style chassis are also commonly used to configure vehicles that lift, haul and place heavy precast concrete structures. We can expect to see tractor and trailer setups, all kinds of boom and crane trucks and even specialty delivery vehicles with all-wheel drive in precast plants across the country.
Whatever your application requirements and product mix may be, knowing your payload requirements and talking with the experts will help to narrow your choices when considering trucks.
Lifting and placing products are the key elements when determining what type and capacity of crane you will choose for your operation. We will look at three distinct models or types of truck- and/or trailer-mounted cranes that precasters use for lifting and placing product, and the unique characteristics of each will be discussed in the following sections.
As usual it’s all about the numbers. Your choice in a crane will ultimately boil down to the size of the product (length, width, height and weight), how far from the vehicle the product will be placed and how much clear space there is between the delivery vehicle and the final installation location at the site.
Cranes can be rated in a variety of ways; however, most manufactures typically rate a maximum lift capacity (pounds, tons or kilograms) at a minimum radial distance (feet or meters) from the center of lift for the crane. They call this quantity the lifting moment, which in simple terms is the maximum weight multiplied by the rating distance.
Crane capacity is not to be confused with crane stability. A crane is always equipped with devices to stabilize a lift. There are many types, but the two common types are outriggers and scissor stabilizers. Outriggers (hydraulically actuated extensions with feet) are rear-mounted and/or front-mounted legs that extend out a few feet beyond both sides of the vehicle and then down to increase the base of the crane to preventing tipping under load.
Scissor stabilizers serve a similar purpose. They are also hydraulically actuated and typically extend downward.
A boom crane is characterized by two or more straight sections of steel that fit inside each other and extend in a telescoping fashion. At the rear-most section is the lifting pivot point for the boom, and the lifting pressure is provided by a large-bore hydraulic cylinder just ahead of the pivot to press the boom upward. A boom base provides a solid mounting point and usually allows a full circular rotation (through 360 degrees). A cable and winch are also used in the lifting mechanism.
These cranes are typically a custom build on a medium- or heavy-duty chassis and provided with mounting on the rear of the truck or trailer. An important characteristic for a boom crane mounted to your truck and/or trailer is the maximum vertical distance from the bed of the vehicle or trailer to underneath the boom. This distance will determine the maximum height of product that can be transported on the equipment.
Knuckle boom crane
The noticeable characteristic of the knuckle boom is the compact, folded package of the assembly when not in use. A knuckle boom crane is a multisection mechanism with pivoting joints between each section and at the base. The outermost portion is made up of multiple tubular steel sections that fit inside each other and provide the crane with extension capability in a telescoping fashion. The middle section is a fabricated steel mast that has pivots at each end. The middle section also is equipped with a hydraulic cylinder to enable it to raise the telescoping end of the boom. The base section is typically fixed with a single pivot point that is shared by the middle section. It can be fitted with either a single or multiple hydraulic cylinder arrangement, depending upon the capacity of the unit. The truck-mounted portion has a rotating base that provides a housing for the outriggers below it. As with the boom crane, a knuckle boom crane can also use a cable and winch in a lift cycle.
Knuckle boom designs are offered in a wide range of capacities to fit your specific requirements.
The A-frame design is equipped with similar auxiliary equipment as the previous two models. Cable and winch assemblies for hoisting the product and outriggers for stabilizing during a lift are standard features with the A-frame and other models.
There is also a wide range of capacities available in an
A-frame, depending upon the size and duty of the delivery truck. This vehicle unloads and places the product straight off the back of the truck via the stationary main beam section that is supported by a steel A-frame mounted to the front and rear of the truck’s bed. The main beam can be a solid single section of steel, or may consist of telescoping multiple sections of solid steel or a lattice-type section.
As with the other crane designs, the A-frame offers a good transportation and placing solution for precasters.
Said very well in the Safety Essentials issue of MC Magazine (“From Customer to Field Set”), “Field safety begins at the plant and continues through delivery and installation.” There are far too many safety aspects to cover in this article; however, safety is found not only in the proper use of the load tables, tie downs, transportation and installation methods of precast products, but also in all of the devices used for lifting and securing the products. Spreader bars, slings, chains, cables, shackles, straps and hooks used to lift the load onto the transport must be verified for capacity and must have an adequate safety factor to ensure a safe lift.
A safety factor of at least 5 is recommended for lifting apparatuses, and such commercially available devices must have the capacity marked on the device. Lifting the precast product properly is just as important as using the proper equipment to lift the product to avoid potential damage
Loads must be properly secured to the transport with appropriate blockage and either nylon straps or chains with guards so as to avoid product damage during shipment. NPCA’s publication “Cargo Securment for the Precast Concrete Industry” outlines proper methods for securing product. Before a load leaves your yard, validate that it is secure as part of the final inspection processes.