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The test also addresses safe hooking steps, fifth wheel locking and height checks, cross-connection consequences, parking practices, and proper backing alignment and trailer support adjustments.",{"@graph":14,"@context":73},[15,34,56],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/document/","Document",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/document/exam/","Exam",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/document/combination-vehicles-practice-test-class-a-cdl/295384/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/combination-vehicles-practice-test-class-a-cdl/295384.png","ImageObject",300,407,{"name":42,"@type":43},"Chloe Bennett","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/pdf","2026-11-04","2026-09-18",true,{"@type":52,"interactionType":53,"userInteractionCount":55},"InteractionCounter",{"@type":54},"ViewAction",12,{"@type":57,"mainEntity":58},"FAQPage",[59,65,69],{"name":60,"@type":61,"acceptedAnswer":62},"What should the emergency line be colored on a combination vehicle?","Question",{"text":63,"@type":64},"Select the option that matches the emergency line color used to prevent mixing up air lines.","Answer",{"name":66,"@type":61,"acceptedAnswer":67},"If the service line disconnects while driving, what happens right away?",{"text":68,"@type":64},"Choose the result that describes immediate effects on tractor or trailer brakes once the service line is open or separated.",{"name":70,"@type":61,"acceptedAnswer":71},"How do you know the trailer is at the right height when hooking up?",{"text":72,"@type":64},"Pick the measurement or alignment condition that matches the specified kingpin and fifth wheel height relationship.","https://schema.org",{"og:url":32,"og:type":75,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":77,"canonical":32},"index,follow",{"doc_id":79,"site_id":7},295384,1789718559,{"code":4,"msg":82,"data":83},"success",[84,88,92,95,100,105,110,115,120,123,127],{"id":22,"doc_module":4,"doc_module_name":25,"category_name":85,"show_sort_weight":86,"slug":87},"Story & Novel",90,"story-novel",{"id":26,"doc_module":4,"doc_module_name":25,"category_name":89,"show_sort_weight":90,"slug":91},"Literature",80,"literature",{"id":33,"doc_module":4,"doc_module_name":25,"category_name":29,"show_sort_weight":93,"slug":94},70,"exam",{"id":96,"doc_module":4,"doc_module_name":25,"category_name":97,"show_sort_weight":98,"slug":99},5,"Comic",60,"comic",{"id":101,"doc_module":4,"doc_module_name":25,"category_name":102,"show_sort_weight":103,"slug":104},6,"Technology",50,"technology",{"id":106,"doc_module":4,"doc_module_name":25,"category_name":107,"show_sort_weight":108,"slug":109},7,"Healthcare",40,"healthcare",{"id":111,"doc_module":4,"doc_module_name":25,"category_name":112,"show_sort_weight":113,"slug":114},8,"Research & Report",30,"research-report",{"id":116,"doc_module":4,"doc_module_name":25,"category_name":117,"show_sort_weight":118,"slug":119},9,"Religion & Spirituality",20,"religion-spirituality",{"id":118,"doc_module":4,"doc_module_name":25,"category_name":121,"show_sort_weight":118,"slug":122},"World Cup","world-cup",{"id":124,"doc_module":4,"doc_module_name":25,"category_name":125,"show_sort_weight":124,"slug":126},10,"Lifestyle","lifestyle",{"id":128,"doc_module":4,"doc_module_name":25,"category_name":129,"show_sort_weight":96,"slug":130},19,"General","general",{"code":4,"msg":82,"data":132},{"doc_id":79,"user_id":133,"nickname":42,"user_avatar":134,"doc_module":4,"category_id":33,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":135,"file_id":136,"file_url":137,"file_type":138,"file_size":139,"view_count":55,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":96,"language":140,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":141,"faqs":142,"seo_title":143,"seo_description":12,"update_tm":80,"read_time":144},962084925782,"https://ap-avatar.wpscdn.com/davatar_9964176cb1d06d4a9deccf72a44ae3dc","Combination Vehicles Practice Test  \nDirections: Read each question carefully and select the answer that best answers the question.  \nNOTE: This test must be taken by all applicants for a “Class A” CDL.  \n1. Air lines on a combination vehicle are often colored to keep from getting them mixed up. The emergency line is:  \nA. Red  \nB. Black  \nC. Blue  \nD. Orange  \n2. There are two things that a driver can do to prevent a rollover. They are: Keep the cargo as close to the ground as possible, and:  \nA. Make sure that the brakes are adjusted properly  \nB. Keep both hands firmly on the steering wheel  \nC. Reduce speed before entering turns  \nD. Keep the fifth wheel free-play loose  \n3. If the service line disconnects while you’re driving, what will happen right away?  \nA. The emergency tractor brakes will come on  \nB. The trailer’s air tank will exhaust through the open line  \nC. The emergency trailer brakes will come on  \nD. Nothing is likely to happen until you try the brakes  \n4. How do you supply air to the air tank on the trailer?  \nA. By pushing in the trailer air supply valve  \nB. By pulling out the trailer air supply valve  \nC. By connecting the emergency line glad hand  \nD. By applying the trolley valve  \n5. With the engine off and the brakes released, a combination vehicle air brake system shouldn’t leak more than how many psi in one minute?  \nA. 1 psi  \nB. 2 psi  \nC. 3 psi  \nD. 4 psi  \n6. You’re hooking a tractor to a semi-trailer and have backed up but are not under it. What should you do before backing under the trailer?  \nA. Hook up the electrical service cable  \nB. Hook up the emergency and service air lines  \nC. Connect the ground cable  \nD. Nothing, back up and secure the fifth wheel to the trailer  \n7. The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means that:  \nA. The trailer will not swing on the fifth wheel  \nB. You cannot set the fifth wheel for proper weight distribution  \nC. The hand valve is released and you may drive away  \nD. The coupling is not correct and should be corrected before driving the coupled unit  \n8. After pushing in the trailer supply valve, you should not move the tractor until the whole air system is:  \nA. Charging  \nB. At normal pressure  \nC. Bled down to half the maximum pressure  \nD. Between 50 and 60 psi  \n9. You cross the air lines when hooking up to an old trailer. What will happen?  \nA. The hand valve will apply the tractor brakes instead of the trailer brakes  \nB. The brake pedal will work the trailer spring brakes instead of the trailer brakes  \nC. If the trailer has no spring brakes, you could drive away but you wouldn’t have trailer brakes  \nD. The brake lights will not come on when the brake pedal is pressed  \n10. How far should you crank up the front trailer supports (dollies) after coupling a semi-trailer?  \nA. Raised ½ way with the crank handle secured  \nB. Raised ¾ way with the crank handle removed  \nC. Fully raised with the crank handle secured  \nD. Three turns off the top with the crank handle secured in its bracket  \n11. You’re driving a combination vehicle when the trailer breaks away and pulls apart the air lines. You should expect the trailer brakes to apply and:  \nA. The tractor to lose all air pressure  \nB. The tractor brakes to keep working properly  \nC. The trailer supply valve to stay open  \nD. The tractor brakes to lock up  \n12. The hand valve should be used to park a combination vehicle:  \nA. When you park at loading docks  \nB. When you are parking for less than one hour  \nC. When parking on a steep grade  \nD. Never  \n13. Air brake equipped trailers made before 1975:  \nA. Usually do not have spring brakes  \nB. Are easier to stop than newer trailers because they are heavier  \nC. Usually need a glad hand converter  \nD. Cannot be operated on interstate highways  \n14. In normal driving, some drivers use the trolley (hand) valve before the brake pedal in order to prevent trailer skids. Which of these statements is true?  \nA. ","cbCaivotUZRjHfxE","https://ap.wps.com/l/cbCaivotUZRjHfxE","pdf",127252,"English","# Combination Vehicles Practice Test\n## Directions\n## Air lines, valves, and emergency behavior\n## Coupling, fifth wheel, and backing procedures\n## Parking, leakage limits, and historical trailer requirements","[{\"question\":\"What should the emergency line be colored on a combination vehicle?\",\"answer\":\"Select the option that matches the emergency line color used to prevent mixing up air lines.\"},{\"question\":\"If the service line disconnects while driving, what happens right away?\",\"answer\":\"Choose the result that describes immediate effects on tractor or trailer brakes once the service line is open or separated.\"},{\"question\":\"How do you know the trailer is at the right height when hooking up?\",\"answer\":\"Pick the measurement or alignment condition that matches the specified kingpin and fifth wheel height relationship.\"}]","Combination Vehicles Practice Test - Class A CDL | PDF",13]