bucket elevator hold back problem

bucket elevator holdback problems during operation

While using bucket elevator, sometimes there is abnormal holdback operation phenomenon during operation, do you know the reason? In fact, during the operation of bucket elevator, sometimes there will be operation stopping inevitably due to malfunction or heavy-loading, even the breakage of link chain or belt could occur, then cause reversal. The reverse operating can cause collision of the bucket and material that remain in the bottom, this could easily cause deformation of bucket and will not function well due to severe damage. Overloading situation is easy to occur if not pay attention to feeding capacity. Under normal circumstances, the bucket of bucket elevator will lift the material from the bottom to the discharge port which is located on top of bucket elevator and then throw out. In order to ensure the production, when designing and manufacturing equipment, manufacturers just consider that the equipment will not reverse under the non-load condition, because bucket of lower part is two more than upper part, which will be much heavier than the upper. In order to prevent the breakage of belt or link chain or reversal occur in the bucket and link chain, especially when the bucket elevator is under the overload condition, the backstop should be installed at the external of bucket elevator in order to avoid the problem of overload. The bucket elevator holdback consists of reverse rod, revolving shaft, retracting spring and dowel pin etc. In the process of normal operation of bucket elevator, the reverse rod will be upswing after hit by the sleeve, it will fall under the action of retracting spring force, then upswing after hit by another sleeve, not affecting the normal operation of equipment. If there is reversal of bucket elevator, the dowel pin will halt the reverse rod, so it will no longer swing down, and the sleeve will also be blocked by the reverse rod, hence the whole link chain could not reverse. If there is too much material spilled inside the body of machine and fall on the reverse rod, it will cause the failure of holdback. If there is too much materials outside the bucket elevator, it will affect the rotation axis of screw. We may see there will be stacked with material in the pit of bucket elevator on the users site, which will seriously affect the operation of the relevant parts of holdback.

preventing the top 3 problems that can stop a bucket elevator - unitrak

Youve purchased and installed a continuous bucket elevator and everythings running fine until Murphy strikes and your elevator and line are halted. What now? Unplanned maintenance interventions, frantic calls to the manufacturer, whatever it takes to get the elevator back up and running. While bucket elevators from reputable OEMs are dependable machines, such unexpected scenarios can happen, and often they can be avoided. This blog highlights the top three reasons that can bring a continuous bucket elevator down, and offers guidance for avoiding these problems.

In many facilities, continuous bucket elevators are workhorse units. In these settings, it is often easy to overlook performing vital Preventive Maintenance (PM) activities. Failure to perform needed PM activities results in parts and components being pushed beyond their expected life-cycles, with resulting parts failure and attendant unplanned downtime.

In a January 2017articlewhich appeared inPowder Bulk Engineeringmagazine, John McDonald, Service Team Leader at UniTrak, highlighted the need to follow an OEMs recommended PM activities and schedule. In that article, John also discussed particular aspects of a continuous bucket elevator that should be regularly inspected to detect signs of premature wear and tear that could lead to failure. This need becomes even more acute in severe service settings where aggressive materials are being moved or the equipment is being used in extreme conditions and temperatures.

Material which spills from buckets as it transits the elevator, or which accumulates in the infeed area due to poor material feeding, can build up to the point where machine operation is halted. Accumulated material can cause buckets to be torn loose from their mounting fasteners, or block the progress of buckets through the elevator, resulting in an overload situation and consequent machine shutdown.

As noted above, continuous bucket elevators from reputable manufacturers are dependable units that can offer excellent uptime and availability if certain basic practices are followed. Following the tips above can help ensure you avoid the problems described above and reduce unplanned equipment stoppages.

UniTrak manufactures the TipTrak line of continuous bucket elevators. These elevators are available in a range of configurations and capacities. TipTrak elevators feature fully interlocking bucket assemblies and a rubberbeltchainwhich never needs tensioning or lubrication. A wide range of options are available to support specific applications. To find out more about TipTrak continuous bucket elevators, pleasecontactour sales team directly.

problems with bucket elevators - biomass engineering & equipment

Manufacturers often choose continuous bucket elevators because these machines seem like the obvious choice. Manufacturers need to handle material gently, they need to move materially vertically; they have limited space to do so; they need to move material quickly; and theyre using a belt conveyor to move product. A bucket elevator will accomplish these things. But it will do so with major drawbacks.

Out of the reasons why manufacturers choose continuous bucket elevators, their use of a belt conveyor typically drives their choice. But belt conveyors are notoriously bad at elevating product. They can only angle up 15 or 16 degrees before product begins rolling back down the belt. Thus, when manufacturers have to elevate product, they either have to use a long conveyor that takes up lots of floorspace (which is neither economical nor fast) or install some type of elevating equipment, such as bucket elevators.

There are two types of bucket elevators: centrifugal and continuous. Centrifugal elevators are commonly used to move grains and other non-fragile materials that weight up to 50lb/sq. ft. With these elevators, buckets dig into a pile of grain and throw the grain at the top of the elevator.

Continuous bucket conveyors dont dig material. The material is conveyed to the bucket elevator and is gravity fed into the buckets, which are commonly attached to a belt. The buckets elevate the product and discharge the product using gravity on the descending side of the elevator.

As said, bucket elevators come with a set of problems. Simply put, they can be a maintenance (and production) nightmare. Theyre complex. They increase the number of gears and parts to keep track of and replace. Theyre hard to clean, difficult to get aligned and flowing at the correct speeds, require tensioning, and on and on.

There are a lot of little things that can go wrong and, when not caught early, can quickly lead to big problems. Manufacturers who use bucket elevators rely on plastic buckets bolted onto rubber belting. As the machines collect material and elevate it, a lot of force is placed on those bolts. If these bolts begin to fail and maintenance doesnt catch it, the buckets can rip off the belt and do a lot of damageand a lot of downtime.

Another small issue is belt tracking. If the belt gets off track a little bit, the belt and the buckets can begin to wear. As the belt wears, it loses its integrity. As the buckets wear, they dont hold material as well. This leads to excess material falling into the bottom of the bucket elevator, which manufacturers either have to discard (waste) or manually feed shovel back into the system (a waste of time).

Jams are one of the most common problems with bucket elevators. Moving products can interlock or catch on the equipment frame, causing it to freeze. The production line must then be shut down and the elevator opened and the jammed material removed before production can continue. Jams can also occur when material builds up inside the bucket elevator shell or housing and eventually clogs the machine.

The good news is that this client knew about another choice: SMART Conveyors. Our drag conveyors eliminate the problems associated with bucket elevators and can replace belt conveyor systems altogether. For one, drag conveyors are easier to maintain than bucket elevators. They have fewer parts, they dont use belts, they wont jam from material buildup, they dont have worn buckets that stop interlocking start catching frame members, they dont employ a belt-drive system that can slip or mistrack

Weve even designed our conveyor for easy maintenance. Maintenance technicians can replace our curve wear strips externally, and our head sections are split, so crews can access the 3-piece, split sprockets with ease. (3-piece, split sprockets let maintenance crews change the sprockets without breaking the chain.)

Weve had conveyors run for years with only routine maintenance performed. Our wear strips rarely need replaced, even on curves. Typically, all maintenance crews have to do to our conveyors is lubricate them.

Elevating materials at steep angles isnt a problem for our conveyors. The conveyors can elevate materials at angles up to verticalwith minimal support structure required. This means that valuable floor space wont be taken up.

Drag conveyors also eliminate the mess associated with bucket elevators. There wont be anything to clean up on the floor or in the conveyor itself. Also, because our conveyors are enclosed, we can make them dust tight. This eliminates debris in the air which workers must breathe, and it makes the conveyor better from a safety point of view, as its easier to prevent and contain fires.

Drag conveyors also handle material gently. Our paddles are designed with fingers that rake the product and keep it from packing together, so it runs smooth through our machine and doesnt get crushed. Its no rougher than transferring the material and dumping it. And unlike an auger/screw conveyor, it also wont chop up or otherwise decompose material.

Material also wont face the constant, harsh grinding from a center-line chain in our conveyor. We use dual chains to pull the paddles through our system that are placed on the conveyor sides outside the path of the material.

Drag conveyors are far superior to bucket elevators for elevating material. If youre tired of your bucket system or are simply weighing your options for material handling, give us a call. Find out for yourself the meaning of our slogan: Superior Engineering. Superior Performance.

Ill need additional information before I can answer the question you posted on our website (Im looking for a conveyor to move sand): Tons per hour of material you need moved Description and density of the material

the root cause of hydraulic cylinder drift

A popular misconception involving hydraulic cylinders is that if the piston seal is leaking, the cylinder will drift. While a leaking piston seal can be the root cause of cylinder drift, the physics involved are often misunderstood.

Fact is, if the piston seal is completely removed from a double-acting cylinder, the cylinder is filled with oil and the ports are plugged, the cylinder will hold its load indefinitely, unless the rod-seal leaks.

In this condition, due to the unequal volume on either side of the piston, fluid pressure equalizes and the cylinder becomes hydraulically locked. Once this occurs, the cylinder can move only if fluid escapes from the cylinder via the rod seal or its ports.

The second exception involves a load hanging on a double-acting cylinder (Figure 2). In this arrangement, the volume of pressurized fluid on the rod side can easily be accommodated on the piston side. But as the cylinder drifts, a vacuum will develop on the piston side due to unequal volumes, and depending on the weight of the load, this vacuum may eventually result in equilibrium that arrests further drift.

Notwithstanding these two exceptions, if a double-acting cylinder's service ports are blocked by a closed-to-actuator spool (Figure 3), and the piston seal does bypass, pressure will eventually equalize on both sides of the cylinder. At this point, a hydraulic lock is effected and no further drift can occur, unless fluid is allowed to escape from the cylinder or cylinder circuit.

Loss of Effective Area Because of the loss in effective area due to pressure now acting on the rod-side annulus area, the static pressure in the cylinder must increase to support the same load. Remember, force developed by a cylinder is a product of pressure and area.

For example, if the load-induced pressure on the piston side of the cylinder was 2,000 PSI and zero on the rod side when the directional control valve closed, assuming no leakage past the spool, the equalized pressure may be 3,000 PSI depending on the ratio of the piston and annulus areas.

Now consider what can happen if this circuit has a service port relief valve (Figure 4) set at 2,500 PSI. As pressure equalizes across the piston seal and the increasing static pressure on the piston side of the cylinder reaches the cracking pressure of the port relief, however the cylinder will still not retract.

A similar situation can occur in circuits with a load control (counterbalance) valve installed. In this circuit, shown in Figure 5, the directional control valve has a float center spool (service ports A and B open to tank).

As previously stated, if the piston seal leaks, unequal volumes of oil on the rod and piston sides of the cylinder indicates hydraulic lock will prevent any noticeable drift. But once again, due to the loss of effective area as a result of the same pressure now acting on the piston and rod-side annulus areas, the static pressure in the cylinder must increase to support the same load.

The magnitude of this pressure increase depends on the ratio of the cylinder's piston and annulus areas. If the increase in static pressure exceeds the set maximum load of the counterbalance valve, the valve will open allowing oil from the piston side of the cylinder to flow to the tank and the cylinder to retract.

Diagnosing Cylinder Drift Therefore, while the root cause of the problem in both examples is the leaking piston seal, the physics is fundamentally different from the general belief. And if the theory is understood, a pressure gauge can be a useful tool for establishing the cause of cylinder drift.

In either of these examples, if the cylinder is drifting but there is no equalization of pressure across the piston seal, the directional control valve or load control valve is the source of the problem.

advice about problem elevators muller beltex

Muller Beltex has many years of experience and global expertise in the bulk and process industry. That is why we, as a renowned knowledge and service provider, are often approached by equipment manufacturers and end users who are encountering problems with their equipment.

Their questions may involve durability, the wish to reduce excessive wear or capacity issues. In this article, we will enter into a specific problem we often come across in more older elevators used in the agricultural sector, which is product taken down again in the return part of a bucket elevator, so called back-legging. What does this mean?

Product that is not correctly or not discharged from the elevator bucket and is therefore dropped back into the down-going elevator leg. This may be because the elevators were designed for example in the nineteen eighties for a capacity of 70 tons per hour at a certain belt speed and the elevator was fed in the up-going elevator leg. At the time, only one type of product was transported with the elevator in question. However, over the following decades, the tonnage may have been increased to perhaps 100 tons per hour, transporting multiple products with a variety of densities at the same belt speed.

In addition the feeding of the elevator could be both in the up-going and also in the down-going leg of the elevator.Because the product is ending up in the elevator boot section, the buckets need to dig up the product from the boot of the elevator, which leads to unnecessary wear and additional stress on the bucket elevator components and the required capacities are no longer realised.

Extensive inspection of the installation allows us to study the problems. We analyse the existing situation and draw up a plan of approach in consultation with our engineering department. This plan of approach is presented to our customer, together with a specified quotation.

Expert calculation of the correct drive and return pulley, elevator bucket, bucket formation, belt speed, and if applicable, adjustment of the construction itself allows us to successfully solve complex problems like the one described above.

how to trouble shoot bucket elevator belt problems?

As a continuous conveying machinery for loose materials conveying equipment, bucket elevator has been widely used in food, feed, chemical and other industries, it is applicable to vertical conveying for powder, granular and small lump materials. The advantages of bucket elevator are: simple structure, high efficiency, low malfunction, etc. However, failure always happens in our daily operation which will affect the working performance. Here we will talk about the failures and troubleshooting of bucket elevator. 1.bucket belt deviation A. Failure cause : the main reason of bucket belt deviation is that when bucket belt is stretched, the adjustment is not timely or not appropriate . B. Troubleshooting: adjust the tensioning device or gravity tensioning device at the bottom of the elevator, make the hopper with appropriate tightness and keep two axis of bucket elevator under parallel. 2. bucket belt slip A. Failure cause: bucket belt is too long or balance weight is too light. B. Troubleshooting :if the bucket belt is too long, you can cut a section of belt and hang it well; If the balance weight is too light, you should add balance weight until you belt slip phenomenon is eliminated.

elevator bucket venting, when & why muller beltex

Venting an elevator bucket aids in bucket fill and discharge with light, fluffy materials. Lightweight, fluffy materials, and those that are extremely dense or flow poorly can be difficult to handle in bucket elevators at high speeds. Because these materials tend to trap air when being handled by an elevator bucket, it is necessary to provide air relief to assist in their filling and discharge. Materials in this category might be various flours, meals, feed mash or screenings. As these materials enter the bucket, air is released through a series of vent holes in the bottom of the bucket allowing for a more complete fill. These vent holes also allow air to re-enter the bucket, which facilitates full release of product into the discharge. Standard hole diameter is equal to the size of the bolt mounting holes. Anything different is considered a custom vent.

A venting bucket can improve the efficiency of some bucket elevators when handling certain products. On dense materials such as lour, meals, and mash feeds, the vents allow air to escape through the cup as it fills, which permits the cup to fill more completely. During discharge, air can return through the cups as it empties, thus preventing a vacuum that could hold some of the products in the cup and cause back-legging.

On extremely light materials such as alfalfa meal, screenings and bran, a vented bucket not only minimizes blowing of the product during loading and discharge, but also reduces air turbulence in the leg as the bucket travels empty down the return side of the elevator. A reduction in air currents minimizes the vacuum which can draw a light product through the down leg and back to the boot.

12 common bucket elevator troubleshooting | m&c

As a kind of conveying equipment with simple structure, low maintenance cost and high conveying efficiency, bucket elevator is widely used in food, medical, chemical and mining industries, and plays an increasingly important role.

In the actual conveying operation, the efficiency of bucket elevator is affected by the problems of slipping, deviation, tearing, returning, low production and abnormal noise. In this article, we will tell 12 types of troubles and solutions of bucket elevator, to help you produce efficiently!

Reduce the amount of material feeding, and strive to feed evenly, if after reducing the amount of feeding, still can not improve skidding, it may be that too much material is accumulated in the machine or the hopper is stuck by foreign bodies.

1. When lifting different materials, the speed of bucket is different: when lifting dry powder and granule, the speed is about 1-2 m/s; when lifting bulk material, the speed is 0.4-0.6 m/s; when lifting wet powder and granule, the speed is 0.6~0.8m/s.

If the bucket runs too fast, the material will be unloaded ahead of time, resulting in material return. According to the lifting material, the speed of the bucket should be reduced appropriately to avoid material return.

The hopper is the bearing component of the hoist, which has higher requirements for its materials, so the materials with good strength should be selected as far as possible during installation. The general hopper is made of ordinary steel plate or galvanized sheet welded or stamped.

The solution is to increase the air outlet, that is, to set up the air outlet above the discharge pipe of the elevator head, and the outlet pipe leads directly to the atmosphere to reduce the dust concentration in the head so that it can not produce powder explosion.