{"id":2699,"date":"2016-05-10T21:35:38","date_gmt":"2016-05-10T21:35:38","guid":{"rendered":"https:\/\/www.bulldogcastors.co.uk\/blog\/?p=2699"},"modified":"2018-11-02T04:11:20","modified_gmt":"2018-11-02T04:11:20","slug":"castor-wheels-roll-resistance","status":"publish","type":"post","link":"https:\/\/www.bulldogcastors.co.uk\/blog\/castor-wheels-roll-resistance\/","title":{"rendered":"Castor Wheels Roll Resistance"},"content":{"rendered":"<h1><span style=\"color: #333399;\"><strong>Castor Wheels Roll Resistance<\/strong><\/span><\/h1>\n<h2><strong>5 Factors affecting the Roll Resistance of a Castor Wheel<\/strong><\/h2>\n<p><em>&#8220;<strong>Castor Wheel manufacturers<\/strong> use a range of different materials and sizes when producing Castor Wheels.\u00a0 The type of Castor Wheel used will determine the roll resistance of the equipment.\u00a0 Within this article you will find an overview of how to control a Castor Wheels roll resistance, calculating roll resistance and the typical values of rolling friction of wheels.&#8221;<br \/>\n<\/em><\/p>\n<p><strong><em>Definition of Roll Resistance \u201c<\/em><\/strong><strong>\u00a0<\/strong><strong>the force resisting the motion when a body (such as a Castor or Wheel)\u00a0rolls\u00a0on a surface.<\/strong><\/p>\n<p>The roll resistance of a piece of equipment mounted on Castor Wheels is related to 7 primary characteristics:<\/p>\n<ul>\n<li><strong>Castor Wheel Material (Rubber, Nylon, Polyurethane)<img loading=\"lazy\" class=\" wp-image-2702 alignright\" src=\"https:\/\/www.bulldogcastors.co.uk\/blog\/wp-content\/uploads\/Deflected-Wheel-300x209.png\" alt=\"Castor Wheel Rolling Resistance\" width=\"284\" height=\"198\" srcset=\"https:\/\/www.bulldogcastors.co.uk\/blog\/wp-content\/uploads\/Deflected-Wheel-300x209.png 300w, https:\/\/www.bulldogcastors.co.uk\/blog\/wp-content\/uploads\/Deflected-Wheel-150x105.png 150w, https:\/\/www.bulldogcastors.co.uk\/blog\/wp-content\/uploads\/Deflected-Wheel.png 633w\" sizes=\"(max-width: 284px) 100vw, 284px\" \/><\/strong><\/li>\n<li><strong>Castor Wheel Size (For example 100mm Diameter Castor Wheel)<\/strong><\/li>\n<li><strong>Flooring Substrate (Concrete, Carpet, Tiles)<\/strong><\/li>\n<li><strong>Flooring Condition (Level, Uneven, Uphill)<\/strong><\/li>\n<li><strong>Castor Wheel Bearings (Plain Bearing, Ball Bearing, Roller Bearing)<\/strong><\/li>\n<li><strong>Inertia (resistance to movement, based on equipment dimension)<\/strong><\/li>\n<li><strong>Total Weight of the Equipment<\/strong><\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<p>Generally a <strong>Castor Wheels low roll resistance<\/strong> is a positive attribute for a piece of equipment, providing ease of use for the operator, reduced user fatigue and reduce wear and stress of the equipment.\u00a0 However it should be noted that a high roll resistance may sometimes be preferable, for example to provide high grip and increased control of equipment.<\/p>\n<p>&nbsp;<\/p>\n<h2><strong>Castor Wheel Friction<\/strong><\/h2>\n<p>Friction is perhaps the main factor to consider when determining the <strong>Roll resistance of a Castor Wheel<\/strong>. Friction is the resistance between two surfaces sliding or rolling against each other. There are several types of friction, including Static, Sliding and Rolling Resistance.\u00a0 In this article we will be focusing on Rolling Friction which is most relevant to the Castor Wheel Industry.<\/p>\n<p>The standard equation for resistive force due to rolling friction can be defined as follows:<\/p>\n<p style=\"text-align: center;\"><strong><img loading=\"lazy\" class=\"size-thumbnail wp-image-2701 aligncenter\" src=\"https:\/\/www.bulldogcastors.co.uk\/blog\/wp-content\/uploads\/Castor-Wheel-Friction-150x37.jpg\" alt=\"Castor Wheel Friction\" width=\"150\" height=\"37\" srcset=\"https:\/\/www.bulldogcastors.co.uk\/blog\/wp-content\/uploads\/Castor-Wheel-Friction-150x37.jpg 150w, https:\/\/www.bulldogcastors.co.uk\/blog\/wp-content\/uploads\/Castor-Wheel-Friction.jpg 152w\" sizes=\"(max-width: 150px) 100vw, 150px\" \/><\/strong><\/p>\n<p><span style=\"color: #333399;\"><strong><em>F<sub>r <\/sub>= Resistance to move i.e. Force (Newton\u2019s)<br \/>\nc = Coefficient of Rolling friction (based on the Materials &amp; Wheel Diameter)<br \/>\nW = Weight of the Equipment<\/em><\/strong><\/span><\/p>\n<p>Based on the above simple equation it can be seen that by reducing the Coefficient of Friction of either the flooring or wheel material (or both), the resistance to move can be reduced.<\/p>\n<p><strong>Example Rolling Coefficients of Wheel Materials (For Guidance Online):<\/strong><\/p>\n<ul>\n<li><strong>Rubber on Concrete \u00a0 &#8211; \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 0.35 to 0.45<\/strong><\/li>\n<li><strong>Nylon on Concrete \u00a0 \u00a0 &#8211; \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 0.03 to 0.04<\/strong><\/li>\n<li><strong>Polyurethane \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 &#8211; \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 0.04 to 0.08<\/strong><\/li>\n<\/ul>\n<p><strong>Rolling resistance of a Castor Wheel<\/strong> mounted machine or equipment is therefore the measure of the friction between floor surface and the tread of the Castors wheel.<\/p>\n<p>Consider a 102Kg (1000N) Trolley on a set of four <strong>Soft Rubber Castors<\/strong> sitting stationary on a rough concrete floor, where the rubber wheels deflect (deform) due to the load put up on them.\u00a0 The rubber deforms onto the uneven flooring surface.\u00a0 At the point of movement, the resistance to move will be relatively high due to the wheel being deflected (i.e. non-circular wheel due to the weight deformation), and secondly due to the soft rubber gripping the uneven floor indentations.\u00a0 In this instance the coefficient of friction will be high, resulting in a high force required to move the equipment. <strong>(I.e. High Castor Wheels Roll Resistance)<\/strong><\/p>\n<p style=\"text-align: center;\"><strong>Example: Fr = 0.4 x 1000N = 400N Resistance<\/strong><\/p>\n<p>Now imagine the opposite, a 100Kg Trolley on a set of four <strong>Hard Nylon Castors<\/strong> sitting on a smooth wooden floor.\u00a0 The Wheel does not deflect under load, and the Flooring is smooth, therefore having low friction.\u00a0 This would result in a very low coefficient of friction and therefore a much lower force required to move the equipment.<strong> (I.e. Low Castor Wheels Roll Resistance)<\/strong><\/p>\n<p style=\"text-align: center;\"><strong>Example: Fr = 0.035 x 1000N = 35N Resistance<\/strong><\/p>\n<p>&nbsp;<\/p>\n<p>The \u201cResistance\u201d is the amount of energy that is dissipated due to friction instead of being converted into movement of the equipment wheels.\u00a0 Therefore the lower the friction, the less energy absorbed, the more energy used to move the equipment.<\/p>\n<p>The <strong>Diameter of the Wheel<\/strong> also has a significant impact on the Castor Wheels roll resistance.\u00a0 The Larger the Wheel, the Lower the Roll Resistance, hence the easier to move.\u00a0 A wheel diameter of 100mm is twice as easy to move compared to a 50mm diameter wheel.\u00a0 Therefore it is always advised to use a bigger wheel as possible, within the height and cost constraints of the project design.<\/p>\n<p>Within the Material Handling Industry, <a href=\"https:\/\/www.bulldogcastors.co.uk\/\">Castors<\/a> and Wheels are used to <strong>reduce the effort (force) required by the operator<\/strong> or user to move a piece of equipment or machinery.\u00a0 The amount of force required has a significant impact on the efficiency of the equipment hence the productivity. Secondly, reducing the force reduced user fatigue and ensures that equipment can be used for longer periods of time without falling foul of manual handling legislation. \u00a0It is therefore important to consider a Castor Wheels Roll Resistance when designing equipment of selecting Castor Wheels.<\/p>\n<h2><strong>Equipment Inertia<\/strong><\/h2>\n<p>Another important factor to consider is the \u201cInertia\u201d of the equipment.\u00a0 This is the initial force required for move a piece of equipment from a stationary position.\u00a0 The inertia force is always higher than the rolling force, as once momentum has started the force required to continue the motion is less. As a rule of thumb, the initial force to start movement is in the order of 2 to 3 times the rolling force.<\/p>\n<p>The Inertia of a piece of equipment can considerably change the amount of force needed to move an object.\u00a0 The Inertia is calculated based on the size and weight of the equipment.\u00a0 Imagine a 30Kg Box, 10cm x 10cm x 10cm, would be much easier to move or push, compared to a 30Kg Box, 100cm x 100cm x 100cm.\u00a0 Therefore not only the weight of the equipment but also the dimensional size of the equipment has a direct effect on the roll resistance due to inertia.<\/p>\n<h2><strong>Castor Wheel Bearings<\/strong><\/h2>\n<p>The bearing in the castor wheel axle can affect the roll resistance of the equipment (note: It does not affect the Inertia).\u00a0 Bearings act to reduce friction between the axle and the wheel.<\/p>\n<p><img loading=\"lazy\" class=\"wp-image-2703 alignleft\" src=\"https:\/\/www.bulldogcastors.co.uk\/blog\/wp-content\/uploads\/bearing.png\" alt=\"castor wheel bearings\" width=\"126\" height=\"125\" srcset=\"https:\/\/www.bulldogcastors.co.uk\/blog\/wp-content\/uploads\/bearing.png 288w, https:\/\/www.bulldogcastors.co.uk\/blog\/wp-content\/uploads\/bearing-150x150.png 150w, https:\/\/www.bulldogcastors.co.uk\/blog\/wp-content\/uploads\/bearing-100x100.png 100w\" sizes=\"(max-width: 126px) 100vw, 126px\" \/> A Plain Bore Bearing Castor will have the axle rotating against the the bore of the wheel, increasing friction, whereas a Roller Bearing Castor Wheel will rotate the axle against the bearings and reduce the friction.\u00a0 It should be noted however that bearings have the least impact on roll resistance, with low friction roller bearings typically reducing total the coefficient of rolling friction by around 0.01.\u00a0 Therefore Wheel bearings should only be used in the most extreme scenarios, or where extended roll after removal of force is required.<\/p>\n<h2><strong>Guide to Selecting the Best Castor Wheel<\/strong><\/h2>\n<ul>\n<li><span style=\"color: #333399;\">Select the Castor based on the Maximum Load per wheel. (consider weight distribution)<\/span><\/li>\n<li><span style=\"color: #333399;\">Consider the Wheel Tread Material Type. For example, Rubber tread for Low Noise &amp;\/or Floor Protection or Nylon for Wheel Wear Resistance.<\/span><\/li>\n<li><span style=\"color: #333399;\">Consider the Environmental Factors<\/span><br \/>\n<span style=\"color: #333399;\"> &#8211; Temperature<\/span><br \/>\n<span style=\"color: #333399;\"> &#8211; Shock &amp; Vibration<\/span><br \/>\n<span style=\"color: #333399;\"> &#8211; Flooring Type<\/span><br \/>\n<span style=\"color: #333399;\"> &#8211; Fluids, Chemicals &amp; Contaminants<\/span><\/li>\n<li><span style=\"color: #333399;\">Choose the maximum possible wheel diameter.<\/span><\/li>\n<li><span style=\"color: #333399;\">Choose a wheel with the required coefficient of roll resistance.<\/span><\/li>\n<li><span style=\"color: #333399;\">Calculate the roll resistance (Consider initial force will be approx. 2 to 3 times higher).<\/span><\/li>\n<li><span style=\"color: #333399;\">Ensure calculated force is within legislation for the operator. For further guidance on UK Legislation check<\/span> <a href=\"http:\/\/www.hse.gov.uk\/msd\/pushpull\/\" rel=\"nofollow\">http:\/\/www.hse.gov.uk\/msd\/pushpull\/<\/a><\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<h3>Bulldog Castors Ltd<\/h3>\n<p>Bulldog Castors Ltd are expertise in the Design &amp; Application of<strong> Castor Wheels for Material Handling<\/strong> &amp; Industrial Equipment.\u00a0 We offer free technical advice including computer modelling and simulation to calculate Castor Wheel Friction, Complex Load Distribution and Shock and Vibration Analysis, and calculating Castor Wheels Roll Resistance<\/p>\n<p>Contact Bulldog Technical Department on +44 (0)116 2970521 or <a href=\"mailto:sales@bulldogcastors.co.uk\">sales@bulldogcastors.co.uk<\/a><\/p>\n<p><strong><a href=\"https:\/\/www.bulldogcastors.co.uk\">Bulldog Castors Ltd \u2013 British Engineering Excellence<\/a><\/strong><\/p>\n<p><!-- Begin MailChimp Signup Form --><\/p>\n<div id=\"mc_embed_signup\">\n<form id=\"mc-embedded-subscribe-form\" class=\"validate\" action=\"\/\/bulldogcastors.us10.list-manage.com\/subscribe\/post?u=2db0084590ba3e49a00c6c59f&amp;id=c050566161\" method=\"post\" name=\"mc-embedded-subscribe-form\" novalidate=\"\" target=\"_blank\">\n<div id=\"mc_embed_signup_scroll\"><strong><label for=\"mce-EMAIL\">Subscribe to our Engineering News Letter<\/label><\/strong><br \/>\n<input id=\"mce-EMAIL\" class=\"email\" name=\"EMAIL\" required=\"\" type=\"email\" value=\"\" placeholder=\"email address\" \/><br \/>\n<!-- real people should not fill this in and expect good things - do not remove this or risk form bot signups--><\/p>\n<div style=\"position: absolute; left: -5000px;\"><input tabindex=\"-1\" name=\"b_2db0084590ba3e49a00c6c59f_c050566161\" type=\"text\" value=\"\" \/><\/div>\n<div class=\"clear\"><input id=\"mc-embedded-subscribe\" class=\"button\" name=\"subscribe\" type=\"submit\" value=\"Subscribe\" \/><\/div>\n<\/div>\n<\/form>\n<\/div>\n<p><!--End mc_embed_signup--><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Castor Wheels Roll Resistance 5 Factors affecting the Roll Resistance of a Castor Wheel &#8220;Castor Wheel manufacturers use a range of different materials and sizes when producing Castor Wheels.\u00a0 The type of Castor Wheel used will determine the roll resistance of the equipment.\u00a0 Within this article you will find an overview of how to control a Castor Wheels roll resistance, calculating roll resistance and the typical values of rolling friction of wheels.&#8221; Definition of Roll Resistance \u201c\u00a0the force resisting the motion when a body (such as a Castor or Wheel)\u00a0rolls\u00a0on a surface. The roll resistance of a piece of equipment mounted on Castor Wheels is related to 7 primary characteristics: Castor Wheel Material (Rubber, Nylon, Polyurethane) Castor Wheel Size (For example 100mm Diameter Castor Wheel) Flooring Substrate (Concrete, Carpet, Tiles) Flooring Condition (Level, Uneven, Uphill) Castor Wheel Bearings (Plain Bearing, Ball Bearing, Roller Bearing) Inertia (resistance to movement, based on equipment dimension) Total Weight of the Equipment &nbsp; Generally a Castor Wheels low roll resistance is a positive attribute for a piece of equipment, providing ease of use for the operator, reduced user fatigue and reduce wear and stress of the equipment.\u00a0 However it should be noted that a high roll resistance may sometimes be preferable, for example to provide high grip and increased control of equipment. &nbsp; Castor Wheel Friction Friction is perhaps the main factor to consider when determining the Roll resistance of a Castor Wheel. Friction is the resistance between two surfaces sliding or rolling against each other. There are several types of friction, including Static, Sliding and Rolling Resistance.\u00a0 In this article we will be focusing on Rolling Friction which is most relevant to the Castor Wheel Industry. The standard equation for resistive force due to rolling friction can be defined as follows: Fr = Resistance to move i.e. Force (Newton\u2019s) c = Coefficient of Rolling friction (based on the Materials &amp; Wheel Diameter) W = Weight of the Equipment Based on the above simple equation it can be seen that by reducing the Coefficient of Friction of either the flooring or wheel material (or both), the resistance to move can be reduced. Example Rolling Coefficients of Wheel Materials (For Guidance Online): Rubber on Concrete \u00a0 &#8211; \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 0.35 to 0.45 Nylon on Concrete \u00a0 \u00a0 &#8211; \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 0.03 to 0.04 Polyurethane \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 &#8211; \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 0.04 to 0.08 Rolling resistance of a Castor Wheel mounted machine or equipment is therefore the measure of the friction between floor surface and the tread of the Castors wheel. Consider a 102Kg (1000N) Trolley on a set of four Soft Rubber Castors sitting stationary on a rough concrete floor, where the rubber wheels deflect (deform) due to the load put up on them.\u00a0 The rubber deforms onto the uneven flooring surface.\u00a0 At the point of movement, the resistance to move will be relatively high due to the wheel being deflected (i.e. non-circular wheel due to the weight deformation), and secondly due to the soft rubber gripping the uneven floor indentations.\u00a0 In this instance the coefficient of friction will be high, resulting in a high force required to move the equipment. (I.e. High Castor Wheels Roll Resistance) Example: Fr = 0.4 x 1000N = 400N Resistance Now imagine the opposite, a 100Kg Trolley on a set of four Hard Nylon Castors sitting on a smooth wooden floor.\u00a0 The Wheel does not deflect under load, and the Flooring is smooth, therefore having low friction.\u00a0 This would result in a very low coefficient of friction and therefore a much lower force required to move the equipment. (I.e. Low Castor Wheels Roll Resistance) Example: Fr = 0.035 x 1000N = 35N Resistance &nbsp; The \u201cResistance\u201d is the amount of energy that is dissipated due to friction instead of being converted into movement of the equipment wheels.\u00a0 Therefore the lower the friction, the less energy absorbed, the more energy used to move the equipment. The Diameter of the Wheel also has a significant impact on the Castor Wheels roll resistance.\u00a0 The Larger the Wheel, the Lower the Roll Resistance, hence the easier to move.\u00a0 A wheel diameter of 100mm is twice as easy to move compared to a 50mm diameter wheel.\u00a0 Therefore it is always advised to use a bigger wheel as possible, within the height and cost constraints of the project design. Within the Material Handling Industry, Castors and Wheels are used to reduce the effort (force) required by the operator or user to move a piece of equipment or machinery.\u00a0 The amount of force required has a significant impact on the efficiency of the equipment hence the productivity. Secondly, reducing the force reduced user fatigue and ensures that equipment can be used for longer periods of time without falling foul of manual handling legislation. \u00a0It is therefore important to consider a Castor Wheels Roll Resistance when designing equipment of selecting Castor Wheels. Equipment Inertia Another important factor to consider is the \u201cInertia\u201d of the equipment.\u00a0 This is the initial force required for move a piece of equipment from a stationary position.\u00a0 The inertia force is always higher than the rolling force, as once momentum has started the force required to continue the motion is less. As a rule of thumb, the initial force to start movement is in the order of 2 to 3 times the rolling force. The Inertia of a piece of equipment can considerably change the amount of force needed to move an object.\u00a0 The Inertia is calculated based on the size and weight of the equipment.\u00a0 Imagine a 30Kg Box, 10cm x 10cm x 10cm, would be much easier to move or push, compared to a 30Kg Box, 100cm x 100cm x 100cm.\u00a0 Therefore not only the weight of the equipment but also the dimensional size of the equipment has a direct effect on the roll resistance due to inertia. Castor Wheel Bearings The bearing in the castor wheel axle can affect the roll resistance of&#8230;<\/p>\n","protected":false},"author":4,"featured_media":2702,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[70,74,57,82],"tags":[89,91,87,92,88,90],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v18.2 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Castor Wheels Roll Resistance - Bulldog Castors Blog<\/title>\n<meta name=\"description\" content=\"Castor Wheels Roll Resistance - The 5 Factors affecting Roll Resistance of Castor Wheels. Friction, Formulas, Bearings &amp; Selection. 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