quarryollogyII.doc

Loading / Excavating Choosing the right loader or excavator requires understanding your operation. Efficient and productive aggregate processing begins, in large part, with equipment selection. A host of factors, including material composition, production requirements, and of course, budget limitations will enter into the decision. The individual at the pit or quarry responsible for making equipment purchasing decisions is best advised to do as much research as possible into the requirements of the operation, his existing fleet, and the equipment that is currently available on the market. Todays heavy equipment manufacturers are up against a idable challenge. Not only must they design machines that incorporate the very latest in available technology, but they have to do so with one eye on the competition. Ironically, as many manufacturers would likely agree, this is the easy part. Satisfying the customer and making sure his or her needs are met during and after the sale are the real challenges. The hydraulic excavator and front-end loader market are full of machines designed to help aggregates producers do their jobs more effectively, both in the areas of productivity and efficiency. While continual technological advancements will mold the machines of the future, rest assured that there is one out there today that will meet your needs. Loaders Following are some basic questions that should be asked before buying a new front-end loader and excavator. 1. What production rate do I want to achieve In selecting a loader, you should first consider the production capability of other components in the material handling system. Select a loader that can handle slightly more than the capacity of the system/equipment that is receiving the material. Required production rates should be carefully examined prior to making a selection. 2. What cycle times do I want to achieve According to Caterpillar, a basic cycle time of .45-.55 minutes is average for an articulated loader hauling loose, granular material on a hard, smooth operating surface with an experienced operator. The basic cycle time for large loaders 4 cu. yd. and up can be slightly longer. Material type, pile height, and other factors may improve or reduce production and should be added to or subtracted from the basic cycle time. For example, in its “Perance Handbook,“ Caterpillar suggests adding .02 minutes to the basic cycle time for mixed material and for material up to 1/8 in. For 1/8-in. to 3/4-in. material, subtract .02 minutes. For material sizes 6 in. and higher, add .03 minutes, and for bank or broken material, add .04 minutes. For pile factors, add .01 minutes for conveyor or dozer piles of 10 ft. or less and .02 for piles dumped by a truck. For constant operation, subtract up to .04 minutes, and for inconsistent operation, add up to .04 minutes. A small loading target will add up to .04 minutes, while a more fragile target will add up to .05 minutes. Using actual job conditions and the above factors, convert total cycle time to cycles per hour using the following ula Cycles Per Hour at 100 Efficiency 60 minutes/Total Cycle Time in Minutes 3. What is the average payload I will be targeting Required payload per cycle can be determined by dividing required hourly production by the number of cycles per hour. 4. What bucket size do I want, and how easy is it to change buckets Once required payload per cycle has been determined, it should be divided by the loose cu. yd. material weight to determine number of loose cu. yd. required per cycle. The bucket size required to handle the required volume per cycle can be found by utilizing what Caterpillar calls the “bucket fill factor.“ The fill factor for loose material varies between 85 to 100 percent. Poor blasted rock has a fill factor between 60-75 percent; average blasted rock, between 75-90 percent; and well-blasted rock, 80-95 percent. The bucket size needed is determined by dividing loose cu. yd. required per cycle by the bucket fill factor. A note Fill factors on wheel loaders can be affected by bucket penetration, breakout force, rack-back angle, bucket profile, bucket teeth or bolt-on replaceable cutting edges. In terms of changing buckets, a number of manufacturers offer couplers and fasteners for quick and easy bucket changeout. 5. What breakout force is necessary Mathematical ulas can be used to determine the breakout force generated from rack-back and from bucket lift. As these ulas are based on specific loader dimensions and can vary from manufacturer to manufacturer, it is best to consult with the dealer to arrive at an exact calculation. 6. Has the manufacturer addressed ergonomics in cab design Practically every wheel loader on the market today offers improved visibility, easy-to-reach, fingertip controls and other perance-enhancing features. Komatsus WA420-3 wheel loader utilizes a hydraulic pilot Proportional Pressure Control valve, which reduces operating effort and lever travel. The units boom lever is equipped with a quick kickdown switch allowing the operator to easily downshift from second to first gear. 7. What warranties do I get Improved designs and better technology have enabled manufacturers to guarantee the perance of their machines in more areas and for longer periods of time than in the past. For details on warranties, check with the dealer. 8. Is the machine capable of electronic diagnostics A number of the machines on the market have in place some of on-board diagnostic equipment consisting of sensors and transmitters which can detect problems with most of the machines major operating systems before they occur, all in the name of eliminating downtime and saving you money. The BM L330C wheel loader from Volvo Construction Equipment features a Contronic monitoring system which provides continuous ination on all of the machines major functions, and is linked to a central warning system to in the operator of any malfunctions. Ination is displayed on a console in front of the operator. 9. What provisions have been made for ease of maintenance As producers attempt to get more and more productivity out of a piece of equipment, maintenance has become a primary concern, and manufacturers have taken strides to make maintenance easier. Kawasaki, for example, has designed its 60ZIV series loaders with standard spin-on filters, remote mounted grease fittings and oil drain to simplify maintenance. Caterpillar provides easy access to service areas on its 980G wheel loader via lockable, ground level service doors. The loaders U-joints are lifetime lubricated, while the hood on the machine tilts 75 degrees for complete access to the engine, cooling system and other major components. 10. How well is the dealer prepared to respond to my needs after the purchase Many manufacturers have in place extensive dealership networks with highly trained personnel that can address and provide guidance on any number of operational issues. Also, a number of manufacturers have instituted 7-day-a-week, around-the-clock parts operations that can receive, fill and turnaround parts orders in less than 24 hours. Excavators Choosing the wrong excavator for a particular application can directly impact productivity. Following are some questions that can aid in the selection process. 1. What are the key perance criteria I need to look at before selecting an excavator Material composition and production requirements are two main considerations. “You want to make sure you have the right machine for the material your handling and whether or not it is well-shot material,“ says Tom Marschall, technical sales manager at Hitachi. “This will impact horsepower, torque ratings, and digging forces. Our dealers are trained to discuss specific applications to help people make the right choice.“ “The most important thing to be concerned with is bucket capacity,“ says Mike Murphy, product manager, excavators for Komatsu. “Youre starting point is the overall production requirement for the operation, and then you consider your existing fleet, what you already have to work with. That will pretty much indicate what size bucket and size of machine youll need.“ 2. How important is “matching“ the excavator to the haul truck “Matching is very important,“ says Marschall. “You want to make sure you have the right machine to load your haulers-You dont want to overload them, and you dont want to under-utilized them. The ultimate goal is to move as much material in as little time as possible, so you want to make sure you match the capacity of your excavators with that of your haulers.“ A simple mathematic calculation can help in this area, says Murphy. “Lets say you have a 50-ton truck, and the material weighs 3,000 lb. per yd.,“ explains Murphy. “You have 100,000 lb. of payload capacity divided by 3,000 lb. per yd. for about 33 yd. If you have a 3-yd. bucket, it will take 11 passes for you to fill that truck, and the excavator is capable generally of 3 passes per minute. So, if you have 11 passes divided by three minutes, you are going to be loading that truck right at four minutes. Lets say, for example, that you want to use a 6-yd. machine; now it will take you two minutes to load. So, the thing you have to decide is if you can live with that four-minute loading time or do you have enough trucks and crusher capacity that you need a bigger excavator.“ 3. What are some of the design features that facilitate maintenance According to Jim Mitchell, John Deere Industrial Equipment, there are several key things to look for here. “Some of the features that make servicing the excavator easier include lubrication banks for greasing pivot points you cant reach from the ground or an on-board service plat,“ Mitchell says. “Others include sight gauges for reservoirs, and seals that extend lubrication intervals and protect important areas such as the top and bottom of the swing bearing and swing drive mechanism.“ “Hitachis machines are designed to make accessing service points easier,“ says Marschall. “Another feature that we have integrated into our machines is the Wiggins Fast Fuel System for oils, fuels and liquids. This system is attached to a hydraulic cylinder that runs off of an electric motor. When you flip a switch, a bar is lowered down which has a number of ports on it. Each port is for a different service, either for draining or filling. All you do is simply connect a hose to a port to fill or drain and you dont have to climb all over the machine.“ According to Murphy, Komatsu machines feature a Trouble Data Memory system. “Our electronic monitor panel computer system will memorize an abnormality within the past 999 hours, and the computer will memorize what went wrong so the technician can determine exactly what the error code means and when it occurred.“ Murphy says the computer can memorize the problem on the monitor panel or a laptop computer, from which internal operating data can be downloaded. Automatic overheat protection and an in-line, high-pressure filter are two other fail-safe measures designed into Komatsu excavators, according to Murphy. 4. Can the dealer who sold me the machine per all of the warranty service “No matter where the machine is located, in whatever territory, our dealers would be able to handle any of the product that we sell and they sell,“ says Marschall. “Komatsu distributors have a full complement of tools and diagnostic equipment,“ adds Murphy. 5. Does the machines hydraulic system permit you to use combined functions without a major penalty in productivity “Todays excavators use variable-displacement pumps, which vary the amount of oil they deliver to the digging, swing and travel functions based on the constantly changing requirements for flow and pressure in the hydraulic system,“ says Mitchell. “Each pump can use up to a specific amount of engine horsepower to pump oil against whatever pressure is required by each function.“ “The ideal situation is for the hydraulic system to use as much available engine horsepower as possible to generate the maximum amount of work in the shortest possible time,“ Mitchell adds. He advises to look for an excavator with a hydraulic system that efficiently uses the most available engine horsepower for optimum productivity, especially when using multiple functions. 6. Is a choice of arms available According to Mitchell, it is important to properly equip the excavator for the job it is expected to do in order to maximize its perance. Two or three arm lengths are available for most excavators, he says. Short arms, Mitchell says, provide maximum crowd forces and bucket capacity and are recommended for production truck loading, mass excavating and tough digging conditions such as areas with high rock content. Medium arms are best suited for a wider variety of work, while a long arm would be the choice for situations where reach and/or digging depth is more important than digging force or high lift capacity. Both Hitachi and Komatsu excavators are available with a choice of arm lengths. 7. How fuel-efficient is the machine Computer control enables the engine to maintain a steady RPM for the best fuel combustion and fuel economy, says Murphy. “The hardest thing on an engine is burying the engine RPM,“ he says. “You want it to sit there and hum like a sewing machine. Thats the best use of an engines capability.“ Marschall says Hitachi machines feature a Fuel Pump Savings System. “The main hydraulic pumps that operate the front arm and travel functions do not go on stroke. In other words, they do not start producing oil until the operator pulls a control handle, and they only produce as much as the operator wants by pulling the handle. What this does is save maintenance because the machine lasts longer; it eliminates heating situations, and it saves fuel because youre only utilizing what you need when you need it.“ 8. Will the dealer or manufacturer offer an operator training program “We offer training with every machine we sell,“ says Marschall. “If, for whatever reason, the local dealer is unable to provide the training, someone from Hitachi will make arrangements to provide the training to the customer. We have people who will go out to the site and train the operator.“ “As a manufacturer, we spend a lot of money training our distributors,“ says Murphy. “We train the trainer and the distributor personnel. We frequently train customers, but its usually on a request-type basis.“ 9. What provisions have been made to operate the machine before purchase “We demonstrate machinery everyday,“ says Murphy. “If you say to us, Im thinking of replacing one of my excavators and Id like to try out a new one for a couple of days to see how I like it, we do this everyday. If you say, Id like to try it out for a month, then the arra