Toward the end of the calendar year, when budgets are running thin, you’re probably scheduling a number of maintenance tasks with a limited crew. Some operations run throughout the year, but there is still the “end of season” period when all the numbers come together. When facing that time of the year, there are five maintenance tasks you may want to expand upon, particularly if you’re operating primary or secondary impact crushers.
1. Check the bearings
Throughout the year, you’ve been taking periodic temperature readings on the bearing housings. The end of the season is a good time to review this data to see if there are any trends developing. Changing the brand or viscosity of the grease lubricant may have positive or negative effects, but it may be necessary due to ambient temperatures. Reviewing the temperature data may also uncover periods where the bearings ran short of grease. Consult your lubricant dealer before mixing various grades or brands of grease.
2. Housing maintenance
Over the course of the season, material builds up on the walls behind the adjusting curtains. The Universal VersaCap and NGS Impactors are equipped with large access doors on the back and top of the crusher housing. This provides unmatched visibility behind the curtains.
3. Curtain liners
The concept of saving money by maneuvering worn liners from one area to another may be economic for some, but you can’t risk losing the integrity of the liner and exposing the soft metal behind it. Generally speaking, any cracked liner is a risk and could evolve into a tramp iron event. Curtain liners are available as chromium alloy castings of various hardness to best suit your application. The softer castings have greater impact resistance (less cracking) but tend to wear faster than harder castings. The harder castings offer significant wear life and resist abrading type wear, but they are susceptible to cracking.
As an alternative to the individual cast curtain liners, McLanahan provides a one-piece full-width liner in a hardness up to the 500 Bhn range. If you’re considering a full-width liner, be sure to give your dealer ample notice. The standard cast liners are maintained in inventories at McLanahan dealers and at the factory. It should also be noted that no special lifting device is required for these individual curtain liners.
4. Hydraulic system
The complete line of Universal impact crushers from McLanahan all offer hydraulic shim adjustment as standard. No more heavy wrenching to adjust the curtains. In fact, there are no wrenches at all. Start up the hydraulic power unit, pull on a lever, and the hydraulic ram provides instant access to the shim pack. The hydraulic system requires minimal maintenance. Replace filters and fluid in accordance with the manual, and check for leaks in the hydraulic lines and connections. Be sure to bleed out all the air if breaking any hose or fitting connections. One of the McLanahan advantages is known as the semi-automatic adjustment feature. This optional feature (available as a retrofit kit), will allow you to raise the curtains while under full load and watch the rock grow on the belt.
If you are operating in a closed circuit and you’re looking to switch your emphasis from chip stone to concrete rock, you can monitor the return load in real-time. Pick your optimum setting by simply letting go of the switch. The curtain cylinder will hold that position.
The semi-auto adjust feature is electric over hydraulic with a common control box with switches. It’s simple and effective, but it does require power to the HPU throughout the shift to stand ready in case of adjustment. The beauty of this inexpensive system, is the fact that you can revert back to the shim adjust mode. Set the shims to hold the new gap setting, retract the cylinder, cut the power to the HPU, and you’re done.
5. Rotor maintenance
Whenever the crusher is open for any reason, take time to observe the condition of the rotor. Take pictures of high wear areas and critical surfaces, and save them for future comparison.
Changes in wear patterns can be caused by a wide variety of factors. Essentially, all impactors do best with even feed across the rotor at a rate that stays consistent. If you observe wear on the hammers or rotor body that becomes a concern, always feel free to contact the folks at McLanahan. Unexpected changes in wear on the rotor assembly can be puzzling at times, but we can help identify causes and recommend cost-effective remedies.
The hammers used in Universal impactors all feature a protruding leading edge. The hammer profile provides a means to hold the output gradation longer through the life of the hammer. The best time to flip the hammers is when you realize the capacity has dropped off or the return load in a secondary loop is growing. This assumes you have adjusted the curtains to keep pace with hammer wear. Generally speaking, every one inch of hammer wear will noticeably affect the output gradation of the crusher. Adjusting to compensate for hammer wear will ultimately reduce fines, prolong capacity, and promote efficiency throughout the system.
With hydraulic assist standard on all Universal impactors, the best means to avoid jamming is to raise and lower the curtains several times a week. This will break the looser bound particles, and if done regularly, may negate further clean-out measures. The shim pack will ensure the gap setting remains unchanged.