Fan and Air Circulator Buying Guide

When researching ways to cool your home, you can consider getting a fan. Fans, also known as air circulators, can be the perfect solution to meet light cooling needs. In more temperate climates, they are an excellent alternative to having an air conditioner that may not see much use. In hotter or more humid climates, fans can help ventilate and dry an area while cooling it, or they can supplement existing air conditioning systems.

 

Size, cooling capacity, intended use, style, and operational noise will all influence how effective a fan will cool your environment. Hence, understanding how fans and air circulators work to keep you comfortable is a key component to choosing the right one for your needs.

 

About Fans

Though fans may seem simple upon first glance, they have more recently become sophisticated cooling systems that help you save on cooling costs, meet versatile needs, and promote energy efficiency. Fans were arguably the first cooling devices created by humans. Today most fans are operated by an electric motor, which turns the blades within a housing unit. Several variations in fan design and intended purpose have greatly enhanced their functionality.

 

Fan Types

There are three main types of fans:

  1. Residential fans are generally meant for personal use.

 

  1. Heavy-Duty fans are found in offices, warehouses, and other workplaces to meet practical needs as well as keep employees comfortable.

 

  1. Water damage restoration fans help dry structures that have sustained water damage and tend to be versatile and powerful.

 

Fan Style and Design

Additionally, fans can be further categorized based on style and design. Fan styles include:

 

  • Tower fans have a long, vertical housing unit that includes a cooling apparatus that runs the length of the fan. They conserve space and offer greater blade protection than more traditional fans.

 

  • Pedestal fans feature a conventional fan design perched on a long stand to reach higher areas than a floor or table fan. They are useful for cooling areas off the ground without needing a desk or shelf for support.

 

  • Table fans can rest on a table, desk, shelf, or other stationary object. These desk fans are generally smaller air circulators that are convenient and mobile.

 

  • Floor fans sit on the floor and have a variety of uses. They tend to be larger than other types of fans and are often used in commercial and industrial applications.

 

  • Personal fans keep you cool in everyday situations. These fans are often placed in bedrooms, workshops, and even cars with a primary purpose of cooling one occupant.

 

  • Misting fans generate water droplets that are then released into the environment and evaporated, cooling the area in the process. These fans are generally used outdoors.

 

Many fan models will fit into more than one of the above categories. If you are just starting to investigate what kind of fan you will need, you should first narrow down the type and style of fan you prefer.

 

Fans vs. Air Conditioners

Fans have a variety of advantages over air conditioner systems. While air conditioners have an overall better cooling capacity than fans and offer a greater degree of control over your cooling experience, fans are more ideal for managing specific cooling tasks and allow for increased portability and convenience. Below are some of the more common benefits of using a fan instead of an AC.

 

  • Cost — As a rule of thumb, fans usually cost less than air conditioners, especially for residential usage. If you are trying to spend economically and wouldn’t necessarily benefit from the added capacity of an air conditioner, purchasing a fan may be the perfect route to take. Fans also cost less to maintain than air conditioners, since fans do not have filters, exhaust systems, and drainage concerns associated with them.

 

  • Efficiency — Fans consume less energy than an air conditioner when cooling a similar-sized same space. Whereas air conditioners create a low volume of air at a high pressure, fans create a high volume of air at a lower pressure. If you are looking to save on energy costs or only need a temporary cooling solution, you would do much better with a fan. Combined with a central air conditioning system, fans can help you save on your energy costs each month.

 

  • Green Living — Because fans don’t require refrigerant and conserve more energy when compared to an AC, they are far easier on the environment than an air conditioning unit. Running a fan is one of the cleanest ways to reduce your carbon footprint as you cool your home or workplace.

 

  • Setup — Air conditioners may involve elaborate exhaust and drainage systems, complicated installation processes, specific window or location requirements, and even professional assistance to setup. Fans operate out of the box. Merely choose a location for your fan and plug it in. Most fans do not require any assembly on your part, and those that do are easily put together.

 

  • Maintenance — Air conditioners often need air filters cleaned and replaced, refrigerant recharged, water drained, and pumps maintained in addition to the regular cleaning and upkeep any home appliance would require. Maintaining a fan involves keeping the blades clean and keeping the fan clean. Wiping it down with regular soap and water will get the job done, and you won’t have to purchase additional items not included with the fan to make sure it lasts. Fans are also far more convenient than ACs to repair and replace should a major incident befall it.

 

  • Portability — Because fans weigh less, require little or no installation, and have fewer external components than most ACs, they can be easily moved from room to room or put away for storage purposes.

 

Maintenance

Compared to other appliances, fans are relatively low-maintenance. The most significant issue related to fan upkeep is preventing dust, dirt, grime, and other buildup on the fan blades. When too many particles accumulate on the blades, the fan will spin slower, spread dust and dirt throughout the room, won’t move air as fast or as far, and will generally reduce the fan’s effectiveness. Too much dust buildup may cause the fan to stop spinning altogether.

 

The best way to avoid particle buildup is to regularly clean the fan blades, housing unit, and any air intake mechanisms. If your fan can be disassembled, simply take it apart and wipe down the various components. Refer to the manufacturer’s user manual when disassembling your fan, as the screws may be hidden or there may be easier methods to reach the blades. If your fan cannot be easily taken apart, try using brushes, sprays, or canned air to remove internal buildup. Take care not to get water on the motor or any other electrical parts.

 

Other measures you can take to prolong the life of your fan include placing it out of reach of children or pets, not running it when it’s not needed, using the fan only as it was intended, securing it from falling over or on top of other items, and giving the fan enough space to provide maximum benefit. Should it become necessary, fans are one of the easiest household appliances to replace.

 

Looking for Best Fans Manufacturer? I Recommend You…

King Fortune Electrical Co., Ltd. has become the most trusted name in industrial desk fan products. To meet the customers’ maximum satisfactions, the company has committed to its uncompromising insistence on excellence, quality and innovation. The superior quality of every King Fortune desk fan is backed by the most dedicated technical service support in the company.

 

If you have any questions or have an interest in King Fortune desk fans, please do not hesitate to send inquiry or contact with King Fortune immediately.

 

 

Article Source: https://www.sylvane.com/fan-buying-guide.html

5 Reasons to Use a PU Caster Wheel in a Heavy Duty Industrial Wheel and Caster Application

PU casters are a popular wheel tread for use on industrial wheels, whether it is in a caster application or drive wheel applications. There are many great reasons to choose PU casters for an industrial wheel or caster application. This article will discuss some of the reasons why PU casters are a popular choice.

 

  1. Noise Reduction

 

PU casters are a popular choice in industrial applications because of their quietness in operation when compared to harder wheels such as steel or cast iron. The polyurethane acts as a shock absorber and helps to cushion the ride and absorb bumps from uneven terrain. The noise levels can be reduced dramatically when using polyurethane instead of steel or cast iron wheels, which can help protect your employees hearing.

 

  1. Load Bearing Capability

 

PU casters are also often utilized for their load bearing capacity when compared to rubber. Polyurethane can provide a greater load bearing capacity while still providing the benefits of a rubber tread, such as noise reduction, shock absorption, and floor protection.

 

  1. Coefficient of Friction

 

Another benefit to PU casters in industrial applications is the coefficient of friction of the material. Polyurethane tends to be a grippy material and can help keep towed carts right-side up, where sliding can be a problem for harder wheel materials. It also provides good traction to drive wheels and helps to reduce the amount of load on the wheel to achieve the desired driving force.

 

  1. Floor Protection

 

PU casters are also chosen in applications where floor protection is critical. The polyurethane will deflect and create a much larger footprint than harder wheel materials, such as nylon. This larger area helps reduce the stress concentration on floors and keep the floors in better shape for a longer period of time. So if your floors are expensive and critical to your operation, a PU caster may be the correct choice for your application.

 

  1. Resistance to Corrosion

 

There are many different types of polyurethanes that have varying levels of resistance to certain chemicals, solvents, or even water. In humid or wet environments, polyurethane can be chosen that will not break down or corrode in the presence of water. In other environments where chemical exposure is a problem, a different type of polyurethane can be used to prolong the life of the industrial wheel.

 

PU casters have many benefits in industrial wheel and caster applications, and the reasons above discuss some of the more popular ones. Polyurethanes can provide resistance to corrosion, floor protection, and noise reduction all while providing a material that can handle a lot of capacity. Switching to a PU caster could have a dramatic impact on the success of your operation.

 

If you have any interest in PU caster wheels, I recommend that you can visit the website of ENJOYING GO Co., Ltd.

 

ENJOY is a professional caster wheel manufacturer in Taiwan. They can provide best quality caster wheels for office chairs and home furniture. Do not hesitate to check out ENJOY’s website and feel free to send inquiry to let them know your requirements.

 

 

Article Source: https://www.casterconcepts.com/solutions/polyurethane-casters/polyurethane-tires-advantages/

Casters for Specific Applications: How and When To Choose Office Chair Caster Wheels

The good news is that you can find casters for office chairs, desks and even workstations to keep things rolling easily.

 

Your employees would love to use chairs and desks that are mobile for the right reasons. If you select the right caster, your office chairs can roll and move around easily and more importantly, quietly without the need of ugly plastic mats.

 

It is also seen that choosing the right office casters can improve workplace ergonomics. This means you can select the right casters and indirectly keep your staff healthy and happy.

 

How Can Technically Advance Office Chair Caster Wheels Positively Affect Your Workplace?

 

Modern office furniture caster wheels can roll and swivel even on carpeted floors. The innovative bearing and wheel design makes it easy for chairs, desks and other office equipment to move over carpeted areas or on floors with rugs with ease.

 

This easy movement makes work more comfortable for employees who have to sit in chairs for extended periods. What’s more interesting to note here is that ease of movement translates into increased productivity and efficiency. Not to forget, you can reduce workplace overexertion.

 

Yes, Office Casters Can Be Quiet!

 

Perhaps the last things you would want in your office are noisy wheels and unwanted squeaky sounds of rolling office chairs and equipment. You can now find ‘practically’ silent office chair casters that can maintain the mobility of your office furniture and equipment without adding to the noise. Remember, ‘silent’ office casters can help your employees stay focused on the task and help them become more productive.

 

No Need for Ugly Carpets

 

With innovative materials used in office chair casters, there will no longer be need for unattractive plastic mats or carpets in the office. “Non marking” casters do not mark or strain the tiles and at the same time, extend the life of your carpet or rug.

 

Because office casters can now be easily replaced, investing in high quality office casters make more financial sense than ever. After all, you no longer have to add the inconvenience of buying new office chairs to your budget.

 

How to Replace Your Office Chair Casters

 

Well, buying new chairs just because your office chair wheel breaks is history now. Chair casters can be easily replaced and replacement casters are affordable as well.

 

Before you proceed with the replacement, make sure:

 

  • The replacement caster wheels you choose match the stem and wheel of your existing caster.
  • Caster wheel you choose for replacement should show best performance on your office floor.

 

Remember that chair casters are differentiated by their diameter. Larger wheels can make your chair sit higher. On the other hand, caster with smaller wheels can lower your chair.

 

Hard wheel casters are designed for use on carpeted floors. Soft wheel casters can be used on hard floors (wooden and tile surfaces).

 

Where Can You Find Quality Caster Wheel Replacement?

 

About this question, I can recommend a manufacturer to you – that’s ENJOYING GO Co., Ltd.

 

ENJOY is a professional caster wheel manufacturer in Taiwan. They offer kinds of caster wheels for office chairs and home furniture. If you need more information about caster wheels, try to visit ENJOY and get more selections of PU caster series.

 

 

Article Source: http://casterwheelguide.com/selecting-caster-wheels/

Choose The Right Paper Towel Dispensers!

A paper towel dispenser is an essential element in any sanitary restaurant kitchen or office restroom. The mounting style and type of dispenser will affect how paper towels are stored, as well as how they are dispensed. Choosing the right paper towel dispenser for your business may seem difficult, but this guide will explain the different designs and types of dispensers so you can make the best choice!

 

Mounting Styles

If there isn’t much room in your bathroom or kitchen, then a surface-mounted or recessed paper towel dispenser would be the best fit. By mounting it to the wall, you save precious counter space and provide convenient access to paper towels right by the sink. The sleek design of recessed models is perfect for tight bathrooms and kitchens where it is best to avoid bulky or cumbersome paper towel dispensers. Both surface-mounted and recessed dispensers are ideal for dispenser / trash can combinations.

 

Countertop paper towel dispensers work well for more spacious bathrooms. With the freedom to pick up countertop dispensers and move them around your hotel or office bathroom, your options are virtually limitless.

 

Dispenser Types

When choosing the right type of dispenser, it is best to think about what type of paper towel you will be dispensing in your commercial kitchen or bathroom. Each dispenser has its benefits and certain paper towels are better suited to fit each dispenser. Paper towel options include standard rolls, center pull rolls, perforated rolls, and folded paper towels.

 

Standard Rolls

Large, standard rolls are perfect for high traffic areas. See the chart below for the dispensers most compatible with this type of roll.

 

DISPENSER TYPE DESCRIPTION BENEFITS
Lever / CrankSB-8522 Paper Towel Dispenser This style is a convenient way to dispense a variety of paper towel lengths; however, these dispensers are not as sanitary as hands free dispensers due to the physical contact between each user and the lever or crank.
  • Allows you to dispense the desired length of paper towel
  • Ideal for light-traffic environments

Hands Free

SB-9523 Auto Paper Towel Dispenser

This dispenser allows customers to pull or tear a desired length without touching the exterior of the dispenser. Motion sensors eliminate the need to pull on a lever or crank, ensuring that each paper towel is only touched by one user and germs are not transferred from user to dispenser.
  • Most hygienic solution
  • Dispenses a set length of paper towel to limit waste

 

 

Center Pull Rolls

Center pull paper towels are a cost-effective and sanitary option. The large roll accommodates high-traffic environments, while the pull-down dispensing method ensures that each paper towel remains clean and unused until it is dispensed by each customer or employee. By removing the center roll, you can then pull each paper towel down from the inside out, further contributing to the sanitary qualities of this paper towel roll.

 

DISPENSER TYPE DESCRIPTION BENEFITS
Center PullCenter Pull Paper Towel Dispenser Customers and employees can pull a single paper towel straight down from the center of the unit. Featuring a large capacity barrel, this dispenser is ideal for high traffic environments.
  • Dispenses single sheets to minimize waste
  • Each user only touches 1 towel
  • Great for high-traffic kitchens or bathrooms

 

Perforated Rolls

With perforated sections, customers and employees can easily tear the desired amount to clean up spills. These rolls are ideal for soaking up messes around your school, office, break room, or kitchen. Soft-to-the-touch, perforated rolls feature a combination of strength, absorbency, and comfort.

 

DISPENSER TYPE DESCRIPTION BENEFITS
CountertopCountertop Paper Towel Holder Made of rustic-looking wrought iron, this paper towel holder is a sturdy yet stylish option for your restaurant or bar.
  • Perfect for individual tables at busy bars and restaurants that serve crab legs, barbeque, and wings
  • Great for countertop applications
Surface-MountedSurface Mounted Paper Towel Holder Easy to mount, this paper towel holder is perfect for dispensing standard, perforated paper towel rolls at the back of the house for commercial kitchens or next to sinks in healthcare facilities.
  • Mounts to walls for convenient placement near sinks

 

 

Folded Paper Towels

Folded paper towels can be used for both countertop and surface-mounted dispensers. Folded paper towels include C-Fold and M-Fold styles. Centerfold paper towels are made to lie on top of each other, while multifold paper towels are made to interlock with each other. The interlocking nature of M-Fold paper towels allows you to fit more paper towels in each dispenser, whereas C-Fold paper towels are easier for guests to separate. Great for dispenser / trash can combinations or countertop baskets and holders, the chart below includes additional information on the benefits of each folded paper towel dispenser.

 

DISPENSER TYPE DESCRIPTION BENEFITS
C-Fold / M-FoldC-Fold / M-Fold Paper Dispenser Conveniently dispenses paper towels one at a time to cut down on waste.
  • Paper towels remain enclosed and sanitary inside the dispenser
  • Easy to separate paper towels
Holders / BasketsPaper Towel Holder / Baskets Guests can easily reach in to access the top paper towel from the holder or basket. Holder/baskets allow for convenient placement near bathroom sinks and they can be easily moved to wipe down counters.
  • Great for countertops
  • Easy mobility
  • Ideal for light-traffic environments
Dispenser / Trash Can CombinationsDispenser / Trash Can Combination This style dispenses paper towels and collects waste. Guests can easily grab one paper towel at a time and quickly dispose of it in the trash can space below. With the ability to dispense and dispose of paper towels in one convenient location, you’ll save space and promote a sanitary environment
  • Great for restrooms
  • Saves space
  • Promotes the highest level of sanitation

 

If you need more information about paper towel dispensers, I recommend that you can try to visit Kingsway Technology Inc.

 

Kingsway, as a professional sanitary products manufacturer, it provides high quality sensor taps, foam soap dispensers, toilet flush valves etc. for you to choose. Also, it manufactures series of washroom accessory, which including paper towel dispensers, roll paper tissue dispensers, and standard soap dispenser. For more details, please feel free to check Kingsway website: www.kingswaytech.com

 

 

Article Source: https://www.webstaurantstore.com/guide/698/types-of-paper-towel-dispensers.html

Ergonomic Benefits of Mesh Office Chairs

The word “ergonomic” originated from the Greek words “ergos” meaning work, and “nomos,” meaning natural laws of. In essence ergonomics is the study of how we can manipulate our work environment to better suit our bodies while we work. Humans were not designed to sit for 8 plus hours a day! Knowing this ergonomists have spent decades studying how to better support the body during this unnatural process of seated task work.

 

There are many aspects involved in creating a functional, ergonomic work environment. There are so many we cannot cover all of them in one article so we’ll focus on the most important piece of ergonomic furniture in your office – YOUR CHAIR. There is only one piece of ergonomic furniture you will always be in contact with and that is your ergonomic chair. Whenever you’re sitting at your desk your body is in constant contact with whatever form of office seating you’ve chosen to use. It’s important that the seat and back surfaces are constructed with materials that reduce pressure points and follows the contours of the body. “Continuous Support” is the foundation of every ergonomic office chair.

 

For years manufacturers focused on using multiple layers of foam with different densities. In 1994 Herman Miller introduced the Aeron Chair using mesh for both the seat and the back. The use of mesh was genius and sparked a revolution in the design and manufacture of office seating. The introduction of mesh to the seat and back yields perfection in continuous support. The mesh follows every curve of the body and cradles the user. The lumbar area of the back is of particular advantage because each user’s body is of different proportions. The mesh gives in the scapular areas and remains tight in the lumbar region which improves posture immensely. This can be achieved with a foam chair but the chair would not be perfect for every user. A chair with mesh on the seat or back can be used by a wider range of body types and can provide continuous support to all of them!

 

Ergonomic mesh chairs are not only looking cool but as you can see they have functional purpose as well. A mesh office chair ability to provide ergonomically correct support to the users is unsurpassed by any other material. There are now many manufacturers providing chairs with mesh used to upholster the seating surfaces. Chairs with mesh seats are generally more expensive because they’re more complex and expensive to manufacture. Many office chairs have mesh backs only and a traditional foam seat. This makes for a more affordable ergonomic mesh chair. Either option is generally better than a traditional office chair with foam cushions because of the properties of mesh upholstery.

 

Leading supplier of mesh office chairs, VOXIM manufactures mesh chair series with years of experiences and insists to provide quality products to clients. We provide two series of mesh office chairs: V-Mesh series and NEUVO series. Their primary feature is to provide a minimalist design in the visual appearance. If you need more information and specification about fashionable and comfortable mesh office chair series, please feel free to contact Voxim.

 

Article Source: http://EzineArticles.com/5779122

Available Types of Nails

Nails come in an amazing variety of size and application range. They range in size from tiny panel pins needing gentle tapping with a small hammer to enormous ones used to affix railway lines to sleepers, which are driven home with sledge hammers. They are used extensively in industry, agriculture, construction, manufacturing, and home use. The common variety is found everywhere from supermarkets to hardware stores and are mostly made of mild steel wire, flattened on the one end and sharpened at the other – you know those objects that cause blue swollen thumbs and foul language? It is however the non-common variety that is so interesting. They can be made of hardened steel, brass or copper and may have decorative heads and grooved or ringed shanks and they are used from furniture upholstery to roof trussing to fixing horse shoes. Some are even – maybe inadvertently – used to flatten car tires or fixing iron rims to wooden wheels. Yes, they are common and sometimes even lowly, but they are also exalted.

 

They also have some amazing names. Consider: Cut clasp, slate, upholstery, clout, ring shank and bright ones among others. They can be driven home by a hammer or a pneumatic tool. Brad nails are more often than not applied with such a tool. The nails are clued together in a string and inserted into the pneumatic tool. The nails are then shot into board or other material using the tool. The heads of brad nails are designed to slightly counter sink and the ensuing hole is later filled with wood putty to conceal the nail. Specialist hardened steel nails used to penetrate concrete is often shot into a wall or roof using a special gun that fires nails rather than bullets. The gun fires blank.22 cartridges which propels the nail into the wall.

 

Clout nails are long, thin ones with a flat large head and are used to fix ceilings to the roof or thin metal to wood. The large head avoids the nail to pull through the material and act as a fastener. Upholstery nails are used for decorative purposes, particularly in the use of leather as a means of upholstery. These nail have large rounded heads which are either copper or brass plated. They are used close to one another so as to create a special luxurious and rustic effect. Clavos nails on the other hand are crafted from iron, are decorative and used mainly as a decorative fixture to rustic doors – think Henry the 8th and the doors to his castle.

 

Roofing nails used to fix corrugated iron to wooden trusses are long shank ones with a large head and fluted shaft, designed to have a lead washer attached. The fluted shaft prevents the nail from loosening in the wind and the washer acts as water proofing. The ones used for fixing asphalt tiles or shingles are also specially designed for the purpose, both with large flat heads. Drywall installation requires special skills and tools. Nails designed for dry walling have rings along the shaft that prevents the nail from pulling out of a dry wall. The heads of such nails are also indented. Picture nails or masonry nails are made of hardened steel and designed to penetrate brick and concrete. These nails are not intended to support heavy weights but pictures etc.

 

Shuen Fuh offers many types of upholstery nails and decorative sofa nails. The material is steel, and the color and size of products can be produced as your requirement. We keep on consistent performance, cost reduction and quality perfection to meet the highest standard of customers’ satisfactions. Welcome to visit the website of Shuen Fuh to browse more upholstery nails and decorative nails relative products.

 

Article Source: http://EzineArticles.com/expert/Samson_Muric/842847

Article Source: http://EzineArticles.com/6712004

 

Mesh Office Chair of Taiwan Fuh Shyan Professional Mesh Chair Manufacturer

Fuh Shyan mesh office chair manufacturer is a professional supplier of mesh office chair has been insisting on providing customer classic quality, good price and excellent service. Fuh Shyan had set up a tool mould department in 2003 with 30 staff work online for fast customer service to new sample development & tool molding. Thus, the ODM & OEM mesh chair cooperation is also very welcome.

Wen Ping Chairs Co., Ltd was established in 2008 under Fuh Shyan Co., Ltd in Chia Yi. The founder, Mr. Tsai following his principles of “Integrity, Sincerity and Sustainable Operation,” laid down long-term company strategies and goals, expanded business territories, and explored new market, and Wen Ping had been growing steadily ever since.

 

SL-A1 Mesh Office Chair
mesh-office-chair-SL-A1-b.jpg
SL-B3 Mesh Office Chair
mesh-office-chair-SL-B3-b.jpg
SL-F4 Mesh Office Chair
mesh-office-chair-SL-F4-b.jpg

 

Fuh Shyan is an old injection factory for the component of mesh office chair. Most of products had past SGS (BIFMA) testing. The answer right and advise proper products to solve customers’ problems from Fuh Shyan. Our sales keep possessing up-to date industrial information and acquire supplier’s technical support at the same time.

Fuh Shyan is a leading distributor and devoted to opening the market for these mesh offic chairs and chair parts. Based on “Good quality, good price, and good service” for the customer, we act immediately and efficiently to the clients for build up a dependable and long-term partnership with our clients. Fuh Shyan is the best partner for you.

Fuh Shyan Office Chair Manufacturer has insisted on its policy of providing customers with top quality products and integrated services before / after sales. We can supplies satisfy customer’s demand ergonomic mesh office chair size, type, shape, material available. We provide the best combination ergonomic mesh chair with high safe quality and competitive price.

mesh chair having a resilience tilt-adjusted device of a backrest includes an upper and a lower casing put together to cover an elastic adjuster which can press one end of elastic members with difference forces. Another end of the elastic members leans against an axle rod which is disposed at the lower end of the backrest supporter. The two ends of the axle rod pass through the casing. The lower end of the backrest is pivotally connected to a predetermined area within the casing as a pivot for swinging. A positioning rod having a rack is passed through the center of the axle rod so as to insert the rack onto the guiding groove of the casing. A positioning piece is arranged upon the rack and can be controlled to move up and down for inserting its end, into the rack. Therefore, when the positioning piece is inserted into or exited from the rack, the backrest supporter can be positioned in a desirable angle after tilting. Also, when the positioning piece is away from the rack, the user can have a different level of resilience against leaning on the backrest by the adjustment of the elastic adjuster as well as the elastic members.