{"id":10641,"date":"2021-04-10T12:14:18","date_gmt":"2021-04-10T10:14:18","guid":{"rendered":"https:\/\/advancedfleetmanagementconsulting.com\/eng\/?p=10641"},"modified":"2021-04-10T12:14:18","modified_gmt":"2021-04-10T10:14:18","slug":"lift-axles","status":"publish","type":"post","link":"https:\/\/advancedfleetmanagementconsulting.com\/eng\/2021\/04\/10\/lift-axles\/","title":{"rendered":"What to Consider When Choosing Lift Axles"},"content":{"rendered":"

Photos: Jim Park<\/span><\/p>\n

There are many things to consider when adding liftable or steerable axles to a truck to increase payload capacity.<\/span><\/p>\n

Liftable and self-steering auxiliary axles can help add payload capacity, but they come with increased weight and additional complexity. An enormous amount of engineering is required to get the right number of axles in the right place on the frame for particular applications in particular jurisdictions. There\u2019s much more to consider beyond how many axles you can squeeze into the available frame space.<\/span><\/p>\n

There is no single lift-axle configuration that works everywhere, because of the wide variety of state and local regulations applicable to axle weights and spreads. Trucks spec\u2019ed for use in Ohio, for example, may not be allowed in Indiana. Local dealers and upfitters will be aware of what configurations are allowable, but if you plan to cross state lines, you may have to settle for a lower common denominator.<\/span><\/p>\n

\u201cFleets want to maximize their payloads, and it\u2019s up to the manufacturer to figure out how to fit steerable\/liftable axles under the truck or trailer,\u201d says Neil Haslam, head of design engineering at Ingersoll Axles. \u201cWe work with the builders on how to install the axle. We also work with the end-users so they\u2019ll know the best way to choose the axle.\u201d<\/span><\/p>\n

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When spec\u2019ing an axle and suspension system for a generic van trailer, there are fewer engineering factors to consider than when specifying a vehicle with a steerable or liftable axle. For example, Haslam says, customers need to weigh the pros and cons of single versus dual tires, the desired suspension style, and even the desired turning angle of the axle.<\/span><\/p>\n

\"Liftable<\/span>
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Liftable axles on trailers for extra capacity are permitted in many jurisdictions, but some require automatic lifting or steering capability.<\/span><\/p>\n<\/figcaption><\/figure>\n

A \u201csuper single\u201d tire (as opposed to a fuel-efficient wide-base single tire) is several inches taller than a standard dual tire, so the suspension travel must be matched to the size of the tire. Were you to consider switching from the taller super singles to a standard tire at some point in the future, you\u2019d risk damaging the suspension by over-extending the air springs.<\/span><\/p>\n

\u201cConversely, a larger tire might not give the needed ground clearance with the axle lifted, say from 4 inches down to 1.5 inches,\u201d says Paul Brown, auxiliary axle marketing manager at Hendrickson. \u201cTire choice is often determined by the frame-to-ground distance, because we have to match the ride height of the suspension to the tire of choice.\u201d<\/span><\/p>\n

Your tire choice can also impact the wheel cut on a steerable axle and the placement of components such as tie-rods and brake chambers, says Brown. \u201cWe can do a pre-set from 20-30 degrees of steer angle. The farther forward you mount the axle, the steeper wheel cut you need, but you still need the frame and component clearance.\u201d<\/span><\/p>\n

Air system capacity is another critical engineering consideration when spec\u2019ing auxiliary axles, especially with multiple lift axles. Section 121 of the Federal Motor Vehicle Safety Standards requires a certain air reservoir capacity based on the size and quantity of brake chambers used. Those calculations are all done by the OEM when the truck is built, but in the case of an aftermarket installation, say with a dump body, the body builder would be responsible for ensuring the finished product meets all the requirements, and that could include upgrading the air compressor to meet the extra demand for air.<\/span><\/p>\n

\u201cWhen you\u2019re talking about lift axles, there are other implications you have to consider, not just the structural loading,\u201d says Dale Kwasniewski, director of rear drivetrain engineering at Meritor. \u201cAdding one or more lift axles is an engineering-intensive process. You don\u2019t just bolt them on and hope for the best. The OEMs are very diligent in that regard, but you should always seek professional advice if you\u2019re adding an axle later in the truck\u2019s life.\u201d<\/span><\/p>\n

And while it may seem like a no-brainer, ensuring the axle will physically fit into the allotted space can be challenging. You have to consider factors such as driveline clearance when the suspension is inflated and deflated, and ensure there\u2019s adequate clearance for the tires while turning (with steerable axles).<\/span><\/p>\n

\u201cFor retrofits, you will need to confirm there is adequate frame rail space for installation,\u201d notes Sibin Luke, business development manager for vocational products at SAF-Holland. \u201cIt\u2019s important to look for components like crossmembers and fasteners that could cause interference issues during installation and operation.\u201d<\/span><\/p>\n

\"Steerable<\/span>
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Steerable axles minimize pavement scrubbing, which states like, and help reduce scrubbing wear on tires, which fleets like.<\/span><\/p>\n<\/figcaption><\/figure>\n

Understanding ratings<\/span><\/h2>\n

You\u2019ll usually hear two different ratings mentioned when spec\u2019ing lift axles, the axle rating and the suspension rating. It\u2019s not uncommon to find, for example, a 26,000-pound axle with a 30,000-pound suspension. The rating for the package \u2014 axle and suspension \u2014 will be that of the lowest-rated component, the axle in this case. Spec\u2019ing a suspension with a heavier rating than the axle could be done for strength and robustness, not just load-bearing capacity.<\/span><\/p>\n

Most of the discussion involving lift axles centers on carrying capacity, but you also have to consider the weight-bearing capacity of the truck when the lift axles are raised, such as when operating on a jobsite. With the axles raised, the drive axles and the steer axle are left to support the full weight of the load. The term most people in the industry use is \u201cjobsite rating.\u201d<\/span><\/p>\n

\u201cWe apply structural ratings to all our vocational tandem and steer axles,\u201d says Kwasniewski. \u201cFor example, a typical 40,000-pound tandem may have a jobsite rating of 55,000 pounds, but other criteria also apply, such as restricting speed to 5 mph or less, and the size and type of tires. That\u2019s the reality of the vocational business, so we have to make sure our axle housings are structurally sound to manage that weight.\u201d<\/span><\/p>\n

The final consideration is where to put the lift-axle control: inside the cab or out on the chassis. Regulations vary around the country, with some insisting the controls be outside the cab beyond the driver\u2019s reach, while others allow controls in the cab.<\/span><\/p>\n

Automation has in some cases made the control a moot point, since deployment is based on weight as determined by the pressure within the air suspension. In the case of steerable axles, there\u2019s often a lock-up or lift switch connected to the reverse light circuit of the transmission. Since steerable axles have 3- to 5-degree reverse caster, they will turn immediately upon reversing, so they must be lifted or locked in the straight position.<\/span><\/p>\n

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by Jim Park<\/a><\/p>\n

Source: https:\/\/www.truckinginfo.com<\/a><\/span><\/p>\n<\/div>\n<\/div>\n

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Photos: Jim Park There are many things to consider when adding liftable or steerable axles to a truck to increase payload capacity. Liftable and self-steering auxiliary axles can help add payload capacity, but they come with increased weight and additional complexity. An enormous amount of engineering is required to get the right number of axles…<\/p>\n","protected":false},"author":3,"featured_media":10642,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[18],"tags":[114],"_links":{"self":[{"href":"https:\/\/advancedfleetmanagementconsulting.com\/eng\/wp-json\/wp\/v2\/posts\/10641"}],"collection":[{"href":"https:\/\/advancedfleetmanagementconsulting.com\/eng\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/advancedfleetmanagementconsulting.com\/eng\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/advancedfleetmanagementconsulting.com\/eng\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/advancedfleetmanagementconsulting.com\/eng\/wp-json\/wp\/v2\/comments?post=10641"}],"version-history":[{"count":1,"href":"https:\/\/advancedfleetmanagementconsulting.com\/eng\/wp-json\/wp\/v2\/posts\/10641\/revisions"}],"predecessor-version":[{"id":10643,"href":"https:\/\/advancedfleetmanagementconsulting.com\/eng\/wp-json\/wp\/v2\/posts\/10641\/revisions\/10643"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/advancedfleetmanagementconsulting.com\/eng\/wp-json\/wp\/v2\/media\/10642"}],"wp:attachment":[{"href":"https:\/\/advancedfleetmanagementconsulting.com\/eng\/wp-json\/wp\/v2\/media?parent=10641"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/advancedfleetmanagementconsulting.com\/eng\/wp-json\/wp\/v2\/categories?post=10641"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/advancedfleetmanagementconsulting.com\/eng\/wp-json\/wp\/v2\/tags?post=10641"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}