Tag Archives: nylon bearing

China 6000Z bearing plastic nylon roller wheels shower door rollers window roller pulley wheels chain pulley

Error:获取返回内容失败,
Your session has expired. Please reauthenticate.

pulley

Types of pulleys and their advantages and disadvantages

There are several types of pulleys. Learn the basic equations of the pulley system. Then learn about the different uses for pulleys. The disadvantages of using pulleys will be covered. Knowing these, you can buy the pulley that suits your needs. Here are some of the best pulley types and their pros and cons.

Basic equations of pulley systems

A pulley system is a mechanism that allows two blocks of a certain mass to be connected by a taut rope. The acceleration of each block is the same in magnitude and direction. The external force acting on each block is the weight of the block (10g) and the tension in the string. The tension between the two blocks is the total tension and the force acting on the pulley is the weight of the two blocks.
This simple mechanism uses two simple equations to explain how the system works. First, the mass of the weight on both sides of the pulley must be the same. When the weight is forced to move, the rope tightens and the second pulley descends. The weight is also attached to the second pulley and must be the same distance as the first pulley. This will result in a speed ratio of 2 times the distance covered by the first pulley.
Second, we have to calculate the force required to lift the object. The lower mass is supported by a wire configuration passing through all pulleys, while the uppermost pulley is used to apply the force. The lower block is used to support the weight. The applied force needs to travel a distance nx to move the weight. This distance, called MA, can be written as:
Once we have gathered the necessary information, we can apply the calculations to the pulley system. We can also use the Mechanical Advantage Calculator to calculate the force on the anchor. To do this, we must apply a force to the load as well as to the pulley itself. Using this equation, we can calculate the force required by the load to lift the load.
pulley

Types of pulleys

There are three basic types of pulleys: movable, fixed and compound. Both types of pulleys translate the force applied to them. The ideal mechanical advantage of pulleys is two. This is because a single movable pulley only doubles the force, whereas a compound pulley doubles or triples the force. This type of pulley is often used with other types of pulleys.
Movable pulls move with the weight of the load, and the force pulling them increases on the lift side. They are often found in utility elevators and construction cranes. These systems are very simple, inexpensive and quiet to use. The force required to lift the object depends on the mechanical advantage of the system. The two most common types of pulleys are listed below. Let's take a closer look at each one.
V-shaped pulleys are used in vehicles and electric motors. These pulleys require a "V" belt to function properly. Some have multiple "V" grooves to avoid slipping. They are used in heavy duty applications to reduce the risk of power slip. These pulleys also have more than one "V" groove. V-belt pulleys are commonly used in vehicles and electric motors.
Composite pulleys are made from more than one type of cable or rope wrapped around the wheel. They can be fixed or hinged and are usually made of stainless steel or bronze. Composite pulleys have multiple layers and can be a single unit or many different components. There are three main types of pulleys: fixed pulleys and composite pulleys. These are the most common types. Almost every type of pulley is used for some type of application.
Fixed pulleys have one advantage over movable pulleys: they change direction as the weight of the load increases. They are typically used in heavy construction equipment. Gun tackles, patio tackles, and stationary tackles are examples of equipment that use a pulley mechanism. These devices are very common and can be found on most modern construction sites. They provide great convenience for lifting large loads.

application

What are the applications of pulleys? Simply put, a pulley is a mechanical device that transforms a difficult task into an easier one. It consists of ropes and pulleys. It is usually used to lift objects. Usually, people wrap a rope around a pulley and pull up to lift the object. One disadvantage of using pulleys is that they require the same force as lifting the object directly.
One of the most popular applications of pulleys is lifting heavy objects. They help people pull up heavy objects and blocks. The system can also be used in seeders, lifts, grinders, etc. Other applications include raising flags, loading cargo, pulling curtains and rock or mountain climbing. Students can learn about the various uses of pulleys and the physics behind them.
Pulleys can be made of many different materials, depending on the application. Some are movable, which means they move with the object they are used to lift. This pulley system can be made of nylon, wire rope or fiber material. The best part about these systems is that they are easy to install and maintain. For a better grasp, use the guide or video tutorial to learn more about the pulley system and how it works.
Tapered pulleys are common in paper mills. They are high-quality pulleys that transmit power to connected parts. They can be dynamic or static and have different balances. Because pulley systems are highly customized, most industrial applications require systems designed specifically for specific applications. In this way, the system is safe, simple and inexpensive. The benefits of this design are endless.
The most common use of pulleys is for motor drives. They are used to minimize noise by applying force to the shaft to reduce the workload. They are also less expensive than gears and do not require lubrication. Furthermore, they can change the direction of the applied force. They are also less expensive than gears and are often used with other components. A screw is a cylindrical member with helical ribs used to connect something.
pulley

shortcoming

Although the pulley system makes it easier to move heavy objects, it still has some drawbacks. When using a pulley system, you must remember that the force required to lift the weight increases with the number of cycles. In addition, the distance between the puller and the heavy object increases, which may lead to accidents. Also, moving heavy objects can be tricky if the rope slips. Pulley systems are not very expensive and can be easily assembled. However, it does require a lot of space.
First, it is not efficient. Besides being inefficient, pulleys produce different forces at different speeds. Fixed pulleys use more force than the load, while movable pulleys move with the load. A movable pulley requires less force than a fixed pulley, but the combined system travels a long distance. Therefore, this method is not as efficient as the fixed method.
Pulleys are not only used in industrial processes. You can see them in various places in your daily life. For example, large construction cranes use pulleys to lift heavy loads. Even flagpoles, blinds, clotheslines, ziplines, motors and climbing equipment use pulleys. Still, despite their advantages, the disadvantages are not too serious.
Another disadvantage of the pulley is its wear and tear. While a pulley's housing is theoretically infinite, its bearings and locking components typically wear out over time. To overcome this problem, a new bearing and locking assembly can be installed. No need to replace the housing and shaft, the entire assembly can be re-bonded and painted to replicate the original look. Alternatively, the pulley can be replaced with a new housing and shaft.
Using pulleys can also reduce the advantage of pulleys. On the other hand, interception and tackle is a system in which two pulleys are connected to each other using ropes. Unlike pulleys, pulley pulley systems can be adjusted in the direction of travel and can move heavy loads up to four times their force when used in hydraulic lifts.

China 6000Z bearing plastic nylon roller wheels shower door rollers window roller pulley wheels     chain pulleyChina 6000Z bearing plastic nylon roller wheels shower door rollers window roller pulley wheels     chain pulley
editor by Cx 2023-06-27

China 3D printer wheels plastic pulley with Bearing nylon pulley wheels with bearings POM H nylon pulley wheels crankshaft pulley

Relevant Industries: Building Material Retailers, Production Plant, Equipment Mend Retailers, Printing Outlets, Building works , 3d printer
Custom-made help: OEM, ODM, OBM
Type: pulley with bearing
Content: Plastic&POM
Surface remedy: POM,easy
Provider: CNC machining
Use: 3d printer,Laser engraving equipment
MOQ: 1pcs
Item title: POM D/H Pulley Bearing
Dimension: 5*24*10mm
High quality Management: Substantial-high quality
OEM: Of course
Payment: T/T,western union,paypal
Packaging Specifics: Packaging Details1. Industrial packaging: 1pc/plastic bag + colour box +carton + pallet 2. Industrial packaging: (1). plastic tube + carton + pallet (2). plastic bag + kraft paper + carton + pallet 3. In accordance to the necessity of consumer.

Name:CNC machining services POM plastic D/H Pulley with bearing POM H pulleySize: 5*24*10 mmMaterial:POM/plasticDelivery time:1.For samples: 1-3days 2.For get: Typically 15-20 daysPayment terms:1: one hundred% TT2: 30% T/T in progress .70% before cargo or against copy of B/L3: Western union and PayPalApplication:Paper making machinery, velocity reducer, railway car axle, equipment box bearing, rolling mill rolling mill rolls,crusher, vibrating monitor, printing machinery, woodworking machinery, all varieties of industryFeature:High precision, minimal sound, higher speed, extended existence, Air Compressor Equipment CZPT Industrial Compressors Variable Rotary Vane 7.5kw 11kw 15kw 22kw Yong CZPT Air Pump substantial dependability, hefty load and high temperature resistance.Service:OEM and ODM(any brand names you want) Connected Goods Packing&Delivery Packaging Details1. Business packaging: 1pc/plastic bag + color box +carton + pallet 2. Industrial packaging: (1). plastic tube + carton + pallet (2). plastic bag + kraft paper + carton + pallet 3. In accordance to the need of buyer. Business Introduction HangZhou Xiehongxin Precision Engineering Co., Ltd. was proven in 2571 and is situated in HangZhou, China,the frontier base of science and technology. We are a business specializing in customizing numerous non-regular higher-precision components parts and finished components for clients.1. Our supplies include stainless metal, brass, copper, iron, aluminum, steel and different plastic materials.2. We currently have all varieties of imported products: cnc drilling and tapping centers, cnc lathes, cnc core shifting devices, large-precision automatic lathes, secondary processing products, and so on. Screening products consists of three-dimensional, projector, hardness tester, salt spray tester, and torque device.3. Our products are mainly utilized in the following industries: mechanical gear, safety equipment, electrical tools, beauty gear, health care equipment, CZPT 2571 Scorching sale pace low noise heavy obligation higher performance 7.5 kw 10 hp 7.5kw 10hp rotary screw air compressor bicycles, electronic cigarettes, 3D printers and sensible houses.4. We have successfully handed the iso9001:2015 program certification.We provide a one-cease provider from style-drawing-proofing-screening-confirmation-mass generation-completed merchandise shipping, and are dedicated to realizing your concepts. Cooperating with us will be your smart decision! FAQ 1) Q: I have not completed enterprise with you before, how can i have faith in your organization?
A: Our company are alibaba.com CZPT provider and passed Field certification by alibaba Group. What is more,we have got authority certificates for ISO9001.Trade Assurance Limit is a lot much more than US$22,000,and it is still increasing up.I hope people above will be persuasive adequate.
two) Q: How is top quality ensured?
A: All our procedures strictly adhere to ISO9001:2008 methods, we have stringent top quality handle from producing to supply,a hundred% inspection by specialist screening centre. Tiny samples could be presented to you for testing.
3) Q: Can i get 1 or more samples?A: Sure, sample orders welcomed. Minimal amount free of charge samples could be offered when we have stocks.4) Q: Do you give any discount rates?
A: Yes, we are going to surely attempt my best to aid you get the greatest price and greatest provider at the exact same time.
five) Q: How to Custom made-made(OEM/ODM)?
A: Remember to ship you solution drawings or samples to us if you have, and we can custom made-created as you needs.We will also offer professional advices of the goods to make the design to be improve the functionality.
Why choose us1) Warranty: our timing pulley's quality is very very good and with ensurance inside 1 calendar year, when you get the products and find quality difficulties, we guarantee you could return it again and free of charge routine maintenance.2) Drawings: you should send out you timing pulleys' drawings to us to get the best quotation If you have no drawings, you should speak to us, then we could perform out CAD drawings and the very best quotation to you ASAP.three) Sample: we take 1 piece sample's order, we could do samples until you' Motorcycle Accessories Motorbike Chain and Sprocket Sets for CZPT VOGE 500R (45T 15T 520H X-Ring 120 Links) re satisfied.4) Confidentiality agreetment: Strictly adherence to shopper confidentiality agreetment for timing pulleys.

pulley

The benefits of using pulleys

A pulley is a mechanical device that converts force into rotation. There are many advantages to using pulleys. Let's take a look at a few of them. This article will describe the advantages, types, applications, and power sources of pulleys. You can then choose the pulley that best suits your specific needs. If you're looking for a new tool to help you with a certain task, this article is for you.

Mechanical advantage

The mechanical advantage of a pulley can be defined as the ratio of applied force to the applied force. The mechanical advantage of a pulley can be calculated by considering several factors, including weight and friction. It can be calculated by the force applied per unit length of rope and the number of pulleys used. In a single-circuit system, the force required to lift a heavy object is equal to the user's body weight.
The mechanical advantage of a pulley can be realized by comparing it to a seesaw. Both uses of rope are suitable for lifting objects. A rope four times heavier than a kilo is four times as effective. Because the forces on both sides of the pulley are equal, a small force is enough to move a large weight a short distance. The same force can be applied to a large mass to lift it several meters.
After introducing the concept of mechanical advantage, learners will practice using the pulley system. In addition to testing the pulley system, they should also calculate its mechanical advantage. Using either the instructor-provided handout or the learner's workbook, students will determine how easily the pulley system functions. Once they have completed the test, they can discuss their results and how the system can be improved. These courses are best completed as part of a mini-unit or as a standalone main course.
The mechanical advantage of the pulley system is proportional to the number of rope loops. This circuit requires the same force as the dual circuit to lift heavy objects. A single lap requires only a third of the force to lift a double lap, while three laps require almost half the energy required for a single lap. The mechanical advantage of the pulley system becomes constant as the number of cycles increases.
The 3:1 Mechanical Advantage system feels like lifting a 300-pound load with three feet of rope. The three-foot-long rope moves the load one foot high. Understanding the mechanical advantages of pulleys is critical for rescuers when trying to create the perfect pulley system. Ideally, the pulley system will be anchored to a nearby rock, tree, pole or person - if the weight is not too heavy.
pulley

Types of pulleys

There are several types of pulleys. V-belt pulleys are the type commonly used in vehicles and electric motors. "V" pulleys require a "V" belt, and some even have multiple V grooves. "V" pulleys are often used in heavy duty applications for power transmission because they reduce the risk of power slippage.
Composite pulleys combine the properties of fixed and movable pulleys. Compound pulleys are able to change the direction of force while requiring relatively low force to move even the heaviest loads. Mechanical advantage is a measure of the effectiveness of a machine or equipment. It can be divided into three categories: force, distance and mechanics. Once you understand how each type works, you can design complex machines.
Fixed pulleys: These pulleys are the most basic type of pulleys. They use ropes and slotted wheels to move with the lifted object. Because they are so simple to set up, lifting heavy objects is a breeze. Although the moving object feels light, it is actually heavier than it actually is. These pulleys are used in construction cranes, utility elevators and many different industries.
Compound Pulley System: A pulley pulley is a combination of two fixed pulleys and one movable pulley. Compound pulley systems are effective for moving heavy objects because they have the largest force multipliers and are flexible enough to change the direction of the force as needed. Composite pulley systems are commonly used in rock climbing, theater curtains and sailing. If you're looking for a pulley system, you can start by evaluating the types of pulleys and their uses.
Construction Pulleys: These are the most basic types of pulleys and have wheel rails. These pulleys can be lifted to great heights and attached to chains or ropes. They allow workers to access equipment or materials from greater heights. They are usually mounted on wheels with axles and secured with ropes. They are essential tools for construction workers. There are many different types of pulleys out there.

energy source

Belts and pulleys are mechanical devices used to transmit energy and rotational motion. The belt is connected to the rotating part of the energy source, and the pulley is mounted on the other. One pulley transmits power to the other, while the other changes the direction of the force. Many devices use this combination, including automobiles, stationary generators, and winches. It is used in many home applications, from conveyors to treadmills. Pulleys are also used for curtains in theater halls.
Pulley systems are an essential part of modern industry and everyday life. Pulleys are used in elevators, construction sites and fitness equipment. They are also used in belt-driven generators as backup power. Despite their simple and seemingly humble beginnings, they have become a versatile tool. From lifting heavy objects to guiding wind turbines, pulley systems are widely used in our daily lives.
The main reason why pulleys are so popular is the mechanical advantage they offer. They can lift a lot of weight by applying very little force over longer distances. For example, a small motor can pull 10 meters of cable, while a large motor can pull 1 meter. Also, the work done is equal to the force times the distance traveled, so the energy delivered to the large motor is the same.
The power source for the pulley system can be cables, belts or ropes. The drive element in a pulley system is usually a rope or cable. A belt is a loop of flexible material that transmits motion from one pulley to another. The belt is attached to the shaft and a groove is cut in the pulley. The belt then transfers energy from one pulley to the other through the system.
pulley

application

A pulley is a mechanical device used to lift heavy objects. They reduce the amount of work required to lift heavy objects and are an excellent choice for many applications. There are several different applications for pulleys, including elevators, grinders, planters, ladder extensions, and mountaineering or rock climbing. Let's take a look at some of the most popular uses for pulleys in modern society. These include:-
A pulley is a mechanical device that changes force. To use, you wrap the rope around it and pull down to lift the object. While this device is very useful, a major limitation of using pulleys is that you still have to apply the same force to lift the object as you would without the pulleys. This is why people use pulleys to move large objects like furniture and cars.
In addition to lifting heavy objects, pulleys are used in elevators, flagpoles and wells. These systems allow people to move heavy objects without straining their backs. Many other examples of pulleys in the home include garage doors, flagpoles, and elevators. They also help raise and lower flagpoles, which can reach several stories high.
There are two basic types of pulleys: movable and fixed. Fixed pulleys are attached to a ceiling or other object using two ropes. Modern elevators and construction cranes use movable pulleys, as do some weight machines in gyms. Composite pulleys combine movable and fixed pulleys to minimize the force required to move heavy objects.
Another type of fixed pulley is the flagpole. A flagpole can support a country, organization, or anything else that needs to be lifted. A taller flagpole creates a prouder moment for those who support it. The operation of the rope and pulley mechanism is very simple. The user simply attaches the flag to the rope, pulls the pulley, and he or she can watch the flag rise and unfold.

China 3D printer wheels plastic pulley with Bearing nylon pulley wheels with bearings POM H nylon pulley wheels     crankshaft pulley	China 3D printer wheels plastic pulley with Bearing nylon pulley wheels with bearings POM H nylon pulley wheels     crankshaft pulley
editor by Cx 2023-06-19

China OEM Timing Belt Pulley Bearing Cable Attachment Elevator Tensioner Nylon Pulley Wheel Slaughter Adjustable Derailer Cast Iron Musculation Station Af Type 3m Pulleys wholesaler

Product Description

    timing belt pulley bearing cable attachment elevator tensioner nylon pulley wheel             slaughter adjustable derailer cast iron musculation station af type 3m pulleys   

Types of Pulley Systems

If you've ever tried to lift a pail of water, you've probably seen the pulley system in action. Pulleys are extremely useful tools for everything from household appliances to heavy industrial machinery. Different kinds of pulley systems are classified according to their amount of motion. Some types have fixed axes, while others have movable axes. Some common uses of pulleys are listed below.

two-wheel pulley

Pulleys are complex structures with thin-walled and thick-walled sections. Therefore, they require specific forging designs. The tool concept for the production of pulleys is shown in Figure 11.6. Using the generated tool, the pulley can be forged into different shapes. Process parameters must be optimized based on material, surface quality and metallographic analysis.
Pulleys are wheels mounted on shafts. Its main function is to assist the movement of heavy objects. A single-wheel pulley can change the direction of the force, enabling a person to pull heavy objects. A dual-wheel pulley distributes the weight evenly across both wheels, allowing it to lift the same weight with half the effort.
The mechanical advantage of a two-wheel pulley is that it reduces the force required by about half. A 100 kg object can be lifted with a force of 500 Newtons. The mechanical advantage of a pulley with 2 wheels is twice that of a single-wheel pulley. However, care should always be taken when using two-wheel pulleys.
Two-wheel pulleys can be fixed or movable. A single wheel pulley can only change direction when the load is placed on 1 side of the wheel. Two-wheel pulleys change direction when lifting a load, requiring half the force. Live wheels are better for heavier loads. The movable pulley can be adjusted with the load, and the load distribution is more uniform. Active pulleys can be used with single-rope or two-wheel pulleys.
A pulley system with 2 wheels is called a compound pulley. This type of pulley system has a complex design that reduces the force required to move the load. Two-wheel pulleys are common in industrial and construction environments. These pulleys require a lot of space to install and operate. Additionally, they require regular maintenance to avoid wear and tear.
pulley

composite pulley

Compound pulleys are used to increase lift. One fixed pulley is attached to the overhead while the other fixed pulley is attached to the load. This setup minimizes the force required to lift weights, allowing you to lift heavier weights. There are several different types of compound pulleys, each with their own strengths and weaknesses. Below are some examples of their application. Some of the most common are listed below.
Composite pulleys are usually made from 2 different types of wheels. The first 1 is fixed and secure. The second type, movable, is attached to something that moves. The third type, compound pulley, is a combination of a movable pulley and a fixed pulley. Below are 3 types of comparisons. The table below compares them and explains their advantages and disadvantages. Composite pulleys are the most versatile of the three.
The number of sheave segments that make up the composite sheave system increases the mechanical advantage of the system. Each segment adds 1 percent of the total weight, and the ideal mechanical advantage is 2 or more. So a compound pulley with 4 segments will lift three-quarters of the weight. This is because the force applied to the load is multiplied by four. The result is a better boost.
While composite pulleys have many uses, they are most commonly used on larger sailboats. These pulleys work by changing the direction of the control wire or by changing the mechanical force of the rope. They also make it easier to lift heavier objects. Composite pulleys are more expensive than simple pulleys, so consider your needs before buying. The advantages of composite pulleys outweigh the disadvantages.
A basic compound pulley is a device consisting of 2 wheels with fixed points. Ropes are looped around the wheels and are used to lift heavy objects. When you pull on the rope, the rope pulls the 2 wheels closer together. Serious injury could result if this equipment is installed incorrectly. Never exceed the lifting capacity of pulleys and other safety devices that may be attached. When using pulleys, be sure to follow the instructions on the mounting hardware to avoid accidents.
pulley

Fixed pulley

Moving pulleys and fixed pulleys are different types of mechanical devices. The movable pulley moves with the object it is used to lift. Because it attaches to the object it is used to lift, it is great for lifting heavy objects. These devices are used in construction cranes and multipurpose elevators. There are many different types of pulleys, and their uses vary widely. Below is a brief overview of these devices.
The simplest pulley set consists of a wheel that is mounted on the ceiling. A rope is attached at 1 end and a person pulls at the other end. The rope is strong enough to keep a person standing while lifting weights. It takes about 200 Newtons of force to lift a 20 kg weight. In contrast, a movable pulley requires a force of 1000N, which makes it easier to lift heavy objects.
Fixed pulleys are another common lifting device. They work by using ropes and slotted wheels attached to the object to be lifted. These devices are convenient to use because they are easy to set up. Moving the scroll wheel doesn't change direction, so it's easier to move objects without putting too much pressure on the back. Unlike a moving rope, a moving object will feel much lighter than its actual weight.
Fixed pulleys are widely used in construction and agriculture. Fixed pulleys can help lift supplies and equipment from scaffolding. These items are often heavy and difficult to lift directly. Fixed pulleys at the top of the scaffolding will allow people at the bottom to lift objects more easily. As a result, those at the bottom are less stressed and more productive. Fixed pulleys will save time and money compared to moving ropes.
Composite pulleys combine fixed and movable pulleys to increase the power of movement. A compound pulley system uses both types of pulleys and enables a person to change direction by reversing the direction of a force. The compound pulley system will save time and effort as the user only has to put in half the effort. Unlike moving ropes, composite pulleys are easy to adjust and are the most versatile system on the market.
pulley

Blocks and tackles

A pulley block system is a rope hoist that uses a set of pulleys mounted on a frame. The blocks are arranged in a row, and the threaded rope is called a pulley. Pulley systems help amplify the tension of the rope and are common in sailboats, cranes and drilling rigs. However, these systems are not without drawbacks.
The pulley pulley system can be equipped with as many pulleys as required. This method allows a person to lift heavy objects. The pulley block system can contain the required number of pulleys to achieve the desired height. The main disadvantage of pulley systems is that they create a lot of friction on the pulley shaft.
Pulley systems use 2 types of pulleys. A movable pulley is attached to the load, allowing it to move with the load. On the other hand, fixed pulleys are fixed on fixed points. Therefore, a pulley block system may consist of multiple pulleys mounted on a shaft. For example, the 2 pulleys attached to the shaft each have their own mechanical advantages.
Several types of tackle systems have been developed in recent centuries. The most basic is the gun mount, which uses 2 pulleys to lift the load. The mechanical advantage of such a system is 2 to 3 times the distance required by the rope to move the load. Depending on how they're assembled, the system can lift 400 pounds with 80 or 100 pounds of force.
Another type of pulley is a combination of multiple wheels. The wheels on pulleys are supported by a housing or frame. The chain is attached to the pulley, and the rope is pulled to lift it. A combined pulley system will have multiple wheels. As the load increases, the force on the pulley also increases. This approach is generally more expensive than intercept and intercept systems.

China OEM Timing Belt Pulley Bearing Cable Attachment Elevator Tensioner Nylon Pulley Wheel Slaughter Adjustable Derailer Cast Iron Musculation Station Af Type 3m Pulleys   wholesaler China OEM Timing Belt Pulley Bearing Cable Attachment Elevator Tensioner Nylon Pulley Wheel Slaughter Adjustable Derailer Cast Iron Musculation Station Af Type 3m Pulleys   wholesaler