"Stone Crusher" clarifies the target equipment, "Material Jamming" points out the core problem, and "Emergency Handling" defines the nature of the content. The three segments "Identification, Safety & Solutions" respectively correspond to the key links of jamming judgment, safe operation, and troubleshooting methods, which can accurately guide readers to quickly understand that this page will provide systematic guidance on how to identify, handle safely, and solve material jamming problems in stone crusher operation.
Material Jamming Types and Instant Identification
By observing the ammeter, listening for abnormal noises, and feeling vibrations, you can determine the cause within 10 seconds. It is also important to record the jamming time and output to facilitate subsequent prevention. This timely identification and recording not only help resolve current jamming issues quickly but also lay a foundation for preventing similar problems in the future, improving the overall operational efficiency of crushing equipment like the jaw crusher and impact crusher.
Large Stones Spanning the Cavity Opening
When a large stone spans the crushing cavity opening, there are obvious signs. The current will rise suddenly, the belt will slip, and the material layer will remain stationary. These phenomena are easy to detect with a little attention. If this situation is not handled in time, it may lead to serious risks such as toggle plate breakage and motor burnout. The toggle plate is an important component of the jaw crusher, and its damage will directly affect the normal operation of the equipment.
Rebar or Steel Beam Wrapping Around the Shaft
Rebar or steel beam wrapping around the shaft often shows symptoms like periodic stalling, a rubber burning smell, and flywheel jitter. The rubber burning smell is a more intuitive sign, reminding operators that there may be a problem. This kind of jamming can cause risks such as shaft bending and belt scrapping. The shaft is a key part for transmitting power, and its bending will affect the stability of the entire equipment operation, especially in machines like the hammer crusher where the rotor shaft plays a core role.
Wet Material Clogging the Cavity
Wet material clogging the cavity is characterized by a sudden drop in crushing capacity, dripping from the discharge port, and adhesion to the cavity wall. These symptoms directly reflect that the material cannot pass through the crushing cavity smoothly. The risks brought by this situation include repeated blockages and accelerated wear of the jaw plates. The jaw plates are vulnerable parts in the crushing process, and accelerated wear will increase maintenance costs and reduce production efficiency, which is a common issue in aggregate processing when dealing with high-moisture materials.
Frozen Block Jamming (Winter)
In winter, frozen block jamming may occur, with symptoms such as the motor failing to start and ice forming on the cavity wall. The motor being unable to start directly stops the equipment. This jamming can lead to risks such as hydraulic cylinder overload and start-up cabinet tripping. This issue is particularly prominent in mining and quarrying operations in cold regions. The hydraulic system is an important part of the crusher's adjustment and protection, and overload will affect its service life.
General 30-Second Shutdown Safety Procedure
The general 30-second shutdown safety procedure is crucial to ensure the safety of operators during maintenance. It includes pressing the emergency stop button, applying a lockout-tagout (LOTO) lock, hanging a "Under Maintenance" warning sign, confirming that the belt is completely stationary, and notifying the loader operator. Each step is designed to prevent accidental startup of the equipment and avoid safety accidents, regardless of whether it is a mobile crusher or a stationary one. Strictly following this procedure can effectively protect the personal safety of maintenance personnel.
Applicable Scenarios of Power Off vs. Inching Reverse
Power off is applicable when it is necessary to enter the cavity for manual prying of materials. At this time, cutting off the power can completely ensure the safety of personnel entering the cavity. Inching reverse is only suitable for situations where the material block is stuck and visible. This method can try to loosen the material block without completely powering off, saving the time of repeated power on and off. However, it must be used under visible conditions to avoid secondary problems, which is a useful technique for small jams in the VSI crusher's crushing cavity.
Remote Emergency Stop Cable Layout
Remote emergency stop cables are arranged with one each on the feeding side and the discharging side, covering a 5-meter range. This layout ensures that operators can quickly trigger the emergency stop from different positions around the equipment, reducing the reaction time in case of emergencies. The 5-meter coverage range is set based on the common operating area around the crusher, maximizing the effectiveness of the emergency stop function, which is a key safety design in both tracked mobile crushers and wheeled ones.
3-Step Cavity Cleaning Method Without Tools
The 3-step cavity cleaning method without tools is simple and practical. First, reverse rotation: press the reverse button for 2-3 seconds and observe if the material block is loose. Reverse rotation can use the reverse force to loosen the stuck material. Then, tapping: use a crowbar or the back of an excavator bucket to lightly tap the side plate to loosen the material through resonance. The resonance effect can make the material block fall off more easily. Finally, reset: run forward with no load for 5 seconds, and restart feeding after the current returns to normal. This step ensures that the equipment returns to a normal operating state before continuing production, and it works well for small jams in cone crushers and jaw crushers alike.
Self-Inspection of Reverse Button Wiring
It is necessary to check whether the interlock of the FWD/REV contactors in the electric control box is normal to prevent short circuits caused by simultaneous activation of forward and reverse rotation. The electrical system is the core of the equipment's operation control, and contactor interlock faults may lead to serious electrical failures, affecting the normal operation of the equipment and even causing safety hazards. Regular self-inspection can find and solve problems in time, which is an important part of daily maintenance for all crushers, including fine crushers.
Tapping Force and Position
The amplitude of the middle of the side plate is the largest, so tapping 2-3 times there is sufficient. Tapping at this position can achieve a better loosening effect with less force. It is forbidden to heavily tap the bearing seat or tie rod spring. The bearing seat is used to support the rotating shaft, such as the eccentric shaft in a jaw crusher, and heavy tapping may damage the bearing; the tie rod spring plays a role in adjusting and buffering, and heavy tapping will affect its performance.
Special Actions for Rebar Wrapping Around the Shaft
For rebar wrapping around the shaft, if the rebar is exposed more than 150 mm after reverse rotation, it can be directly pulled out with cut-resistant gloves. If it is still tightly wrapped, use a 1.5-meter crowbar to lever it loose and then reverse rotation again. For excessively long rebar, use oxygen cutting to segment it, and clear combustible materials that may be splashed before cutting. These actions are targeted to solve the problem of rebar wrapping, which is a common issue in C&D waste recycling where rebars are often mixed in, and they help protect key components like the rotor in hammer crushers.
Homemade "Rebar Hook" Tool
A homemade "rebar hook" tool can be made with a 20 mm round steel bent into a hook, 1.2 meters in length, and can be welded on-site in 5 minutes. This simple tool is very practical for pulling out rebars, improving the efficiency of rebar removal. The on-site welding production allows for quick manufacturing when needed, without the need for complex processing procedures, making it a handy accessory for operators of PCX fine crushers and other machines that process construction waste.
Preventing Secondary Wrapping
To prevent secondary wrapping, a 150 mm × 150 mm rebar grid can be installed at the entrance of the jaw crusher, and the grid welds should be checked daily before the shift. The rebar grid can block larger rebars from entering the crushing cavity, fundamentally reducing the possibility of rebar wrapping. Daily inspection of welds ensures that the grid remains intact and effective, which is a cost-effective prevention measure in cement manufacturing raw material crushing lines.
60-Second Solution for Wet Material Clogging the Cavity
For wet material clogging the cavity, the 60-second solution is to stop feeding, run idly for 10-15 seconds, then add 200-300 kg of dry material to flush the cavity. After resuming feeding, reduce the flow by 20% and observe for 3 minutes. Stopping feeding and idling allows the remaining wet material to be further crushed and discharged. Adding dry material can absorb moisture and flush the cavity wall, reducing adhesion. Reducing the flow after resuming feeding gives the equipment a buffer period to avoid re-clogging, which is especially useful for roll crushers that are more prone to wet material adhesion.
On-Site Dry Material Sources
On-site dry materials can come from dismantled floor precast blocks, dry backfill soil, and manufactured sand. These materials are easily available on construction sites or mining areas, providing a convenient source for flushing the cavity when wet material clogging occurs. Using local materials can save the cost and time of transporting dry materials from other places, which is a practical tip for limestone crushing operations that may encounter unexpected rainfall.
Measures to Prevent Wet Materials
Measures to prevent wet materials include covering the stockyard with a shed, setting the drainage ditch slope to 2%, and having the loader take dry materials from the upper layer first. Covering the stockyard can prevent rainwater from wetting the materials; a reasonable drainage ditch slope ensures smooth drainage of rainwater and avoids water accumulation in the stockyard; taking upper dry materials first reduces the chance of using wet materials, fundamentally reducing the possibility of wet material clogging. These measures are particularly important for maintaining stable crushing ratios in granite crushing plants, where material moisture content significantly affects product quality.
Emergency Heating for Frozen Block Jamming
For frozen block jamming, emergency heating can be done by preheating the cavity opening with a hot air blower or diesel torch for 3-5 minutes. However, it is forbidden to let an open flame directly contact the belt and wires. Preheating can melt the ice, making the frozen block loose and easy to handle. Avoiding direct contact of open flames with belts and wires prevents fire and damage to these components, which is a critical winter operation step for tracked mobile crushers working in cold climates.
Notes for Motor Start-Up at Low Temperatures
When starting the motor at low temperatures, the hydraulic oil should be heated to above 15°C, and idling forward and reverse should be done twice each. Heating the hydraulic oil ensures that the hydraulic system can work normally; idling forward and reverse helps lubricate the internal components of the motor and reduces the starting load, protecting the motor. This is especially important for the main shaft lubrication system of cone crushers, which is sensitive to low temperatures.
Safety Locks and Tool List
The safety locks and tool list includes 2 LOTO locks, 1 pair of insulated gloves, 1 crowbar, 1 rebar hook, and 1 oxygen cutting kit. These tools and locks are essential for safe maintenance work. LOTO locks and insulated gloves ensure operator safety during electrical operations; crowbars and rebar hooks are used for material loosening and removal; the oxygen cutting kit is used for handling longer rebars. Having these tools readily available is a basic safety requirement for any impact crusher or jaw crusher maintenance team.
2-Minute Pre-Shift Inspection Form
The 2-minute pre-shift inspection form includes calibrating the ammeter zero, testing the reverse button, checking that the warning sign is in place, and ensuring the crowbar is placed at a fixed point. Calibrating the ammeter zero ensures accurate current measurement; testing the reverse button ensures its normal operation when needed; checking the warning sign and crowbar placement ensures that safety facilities and tools are available when needed. This short inspection can find potential problems in advance and ensure the normal start-up of the shift, whether it is for a jaw crusher or an impact crusher.