Why are mechanical brakes often used on cranes? | Numerade (2024)

`); let searchUrl = `/search/`; history.forEach((elem) => { prevsearch.find('#prevsearch-options').append(`

${elem}

`); }); } $('#search-pretype-options').empty(); $('#search-pretype-options').append(prevsearch); let prevbooks = $(false); [ {title:"Recently Opened Textbooks", books:previous_books}, {title:"Recommended Textbooks", books:recommended_books} ].forEach((book_segment) => { if (Array.isArray(book_segment.books) && book_segment.books.length>0 && nsegments<2) { nsegments+=1; prevbooks = $(`

  • ${book_segment.title}
  • `); let searchUrl = "/books/xxx/"; book_segment.books.forEach((elem) => { prevbooks.find('#prevbooks-options'+nsegments.toString()).append(`

    ${elem.title} ${ordinal(elem.edition)} ${elem.author}

    `); }); } $('#search-pretype-options').append(prevbooks); }); } function anon_pretype() { let prebooks = null; try { prebooks = JSON.parse(localStorage.getItem('PRETYPE_BOOKS_ANON')); }catch(e) {} if ('previous_books' in prebooks && 'recommended_books' in prebooks) { previous_books = prebooks.previous_books; recommended_books = prebooks.recommended_books; if (typeof PREVBOOKS !== 'undefined' && Array.isArray(PREVBOOKS)) { new_prevbooks = PREVBOOKS; previous_books.forEach(elem => { for (let i = 0; i < new_prevbooks.length; i++) { if (elem.id == new_prevbooks[i].id) { return; } } new_prevbooks.push(elem); }); new_prevbooks = new_prevbooks.slice(0,3); previous_books = new_prevbooks; } if (typeof RECBOOKS !== 'undefined' && Array.isArray(RECBOOKS)) { new_recbooks = RECBOOKS; for (let j = 0; j < new_recbooks.length; j++) { new_recbooks[j].viewed_at = new Date(); } let insert = true; for (let i=0; i < recommended_books.length; i++){ for (let j = 0; j < new_recbooks.length; j++) { if (recommended_books[i].id == new_recbooks[j].id) { insert = false; } } if (insert){ new_recbooks.push(recommended_books[i]); } } new_recbooks.sort((a,b)=>{ adate = new Date(2000, 0, 1); bdate = new Date(2000, 0, 1); if ('viewed_at' in a) {adate = new Date(a.viewed_at);} if ('viewed_at' in b) {bdate = new Date(b.viewed_at);} // 100000000: instead of just erasing the suggestions from previous week, // we just move them to the back of the queue acurweek = ((new Date()).getDate()-adate.getDate()>7)?0:100000000; bcurweek = ((new Date()).getDate()-bdate.getDate()>7)?0:100000000; aviews = 0; bviews = 0; if ('views' in a) {aviews = acurweek+a.views;} if ('views' in b) {bviews = bcurweek+b.views;} return bviews - aviews; }); new_recbooks = new_recbooks.slice(0,3); recommended_books = new_recbooks; } localStorage.setItem('PRETYPE_BOOKS_ANON', JSON.stringify({ previous_books: previous_books, recommended_books: recommended_books })); build_popup(); } } var whiletyping_search_object = null; var whiletyping_search = { books: [], curriculum: [], topics: [] } var single_whiletyping_ajax_promise = null; var whiletyping_database_initial_burst = 0; //number of consecutive calls, after 3 we start the 1 per 5 min calls function get_whiletyping_database() { //gets the database from the server. // 1. by validating against a local database value we confirm that the framework is working and // reduce the ammount of continuous calls produced by errors to 1 per 5 minutes. return localforage.getItem('whiletyping_last_attempt').then(function(value) { if ( value==null || (new Date()) - (new Date(value)) > 1000*60*5 || (whiletyping_database_initial_burst < 3) ) { localforage.setItem('whiletyping_last_attempt', (new Date()).getTime()); // 2. Make an ajax call to the server and get the search database. let databaseUrl = `/search/whiletype_database/`; let resp = single_whiletyping_ajax_promise; if (resp === null) { whiletyping_database_initial_burst = whiletyping_database_initial_burst + 1; single_whiletyping_ajax_promise = resp = new Promise((resolve, reject) => { $.ajax({ url: databaseUrl, type: 'POST', data:{csrfmiddlewaretoken: "mEv8rLXtVKV8Sxel0pfRZ4RzFiCLjJS5KZmUns7WFbY7bBV9aPxobAaY6lJUUmoe"}, success: function (data) { // 3. verify that the elements of the database exist and are arrays if ( ('books' in data) && ('curriculum' in data) && ('topics' in data) && Array.isArray(data.books) && Array.isArray(data.curriculum) && Array.isArray(data.topics)) { localforage.setItem('whiletyping_last_success', (new Date()).getTime()); localforage.setItem('whiletyping_database', data); resolve(data); } }, error: function (error) { console.log(error); resolve(null); }, complete: function (data) { single_whiletyping_ajax_promise = null; } }) }); } return resp; } return Promise.resolve(null); }).catch(function(err) { console.log(err); return Promise.resolve(null); }); } function get_whiletyping_search_object() { // gets the fuse objects that will be in charge of the search if (whiletyping_search_object){ return Promise.resolve(whiletyping_search_object); } database_promise = localforage.getItem('whiletyping_database').then(function(database) { return localforage.getItem('whiletyping_last_success').then(function(last_success) { if (database==null || (new Date()) - (new Date(last_success)) > 1000*60*60*24*30 || (new Date('2023-04-25T00:00:00')) - (new Date(last_success)) > 0) { // New database update return get_whiletyping_database().then(function(new_database) { if (new_database) { database = new_database; } return database; }); } else { return Promise.resolve(database); } }); }); return database_promise.then(function(database) { if (database) { const options = { isCaseSensitive: false, includeScore: true, shouldSort: true, // includeMatches: false, // findAllMatches: false, // minMatchCharLength: 1, // location: 0, threshold: 0.2, // distance: 100, // useExtendedSearch: false, ignoreLocation: true, // ignoreFieldNorm: false, // fieldNormWeight: 1, keys: [ "title" ] }; let curriculum_index={}; let topics_index={}; database.curriculum.forEach(c => curriculum_index[c.id]=c); database.topics.forEach(t => topics_index[t.id]=t); for (j=0; j

    Solutions
  • Textbooks
  • `); } function build_solutions() { if (Array.isArray(solution_search_result)) { const viewAllHTML = userSubscribed ? `View All` : ''; var solutions_section = $(`
  • Solutions ${viewAllHTML}
  • `); let questionUrl = "/questions/xxx/"; let askUrl = "/ask/question/xxx/"; solution_search_result.forEach((elem) => { let url = ('course' in elem)?askUrl:questionUrl; let solution_type = ('course' in elem)?'ask':'question'; let subtitle = ('course' in elem)?(elem.course??""):(elem.book ?? "")+"    "+(elem.chapter?"Chapter "+elem.chapter:""); solutions_section.find('#whiletyping-solutions').append(` ${elem.text} ${subtitle} `); }); $('#search-solution-options').empty(); if (Array.isArray(solution_search_result) && solution_search_result.length>0){ $('#search-solution-options').append(solutions_section); } MathJax.typesetPromise([document.getElementById('search-solution-options')]); } } function build_textbooks() { $('#search-pretype-options').empty(); $('#search-pretype-options').append($('#search-solution-options').html()); if (Array.isArray(textbook_search_result)) { var books_section = $(`
  • Textbooks View All
  • `); let searchUrl = "/books/xxx/"; textbook_search_result.forEach((elem) => { books_section.find('#whiletyping-books').append(` ${elem.title} ${ordinal(elem.edition)} ${elem.author} `); }); } if (Array.isArray(textbook_search_result) && textbook_search_result.length>0){ $('#search-pretype-options').append(books_section); } } function build_popup(first_time = false) { if ($('#search-text').val()=='') { build_pretype(); } else { solution_and_textbook_search(); } } var search_text_out = true; var search_popup_out = true; const is_login = false; const user_hash = null; function pretype_setup() { $('#search-text').focusin(function() { $('#search-popup').addClass('show'); resize_popup(); search_text_out = false; }); $( window ).resize(function() { resize_popup(); }); $('#search-text').focusout(() => { search_text_out = true; if (search_text_out && search_popup_out) { $('#search-popup').removeClass('show'); } }); $('#search-popup').mouseenter(() => { search_popup_out = false; }); $('#search-popup').mouseleave(() => { search_popup_out = true; if (search_text_out && search_popup_out) { $('#search-popup').removeClass('show'); } }); $('#search-text').on("keyup", delay(() => { build_popup(); }, 200)); build_popup(true); let prevbookUrl = `/search/pretype_books/`; let prebooks = null; try { prebooks = JSON.parse(localStorage.getItem('PRETYPE_BOOKS_'+(is_login?user_hash:'ANON'))); }catch(e) {} if (prebooks && 'previous_books' in prebooks && 'recommended_books' in prebooks) { if (is_login) { previous_books = prebooks.previous_books; recommended_books = prebooks.recommended_books; if (prebooks.time && new Date().getTime()-prebooks.time<1000*60*60*6) { build_popup(); return; } } else { anon_pretype(); return; } } $.ajax({ url: prevbookUrl, method: 'POST', data:{csrfmiddlewaretoken: "mEv8rLXtVKV8Sxel0pfRZ4RzFiCLjJS5KZmUns7WFbY7bBV9aPxobAaY6lJUUmoe"}, success: function(response){ previous_books = response.previous_books; recommended_books = response.recommended_books; if (is_login) { localStorage.setItem('PRETYPE_BOOKS_'+user_hash, JSON.stringify({ previous_books: previous_books, recommended_books: recommended_books, time: new Date().getTime() })); } build_popup(); }, error: function(response){ console.log(response); } }); } $( document ).ready(pretype_setup); $( document ).ready(function(){ $('#search-popup').on('click', '.search-view-item', function(e) { e.preventDefault(); let autoCompleteSearchViewUrl = `/search/autocomplete_search_view/`; let objectUrl = $(this).attr('href'); let selectedId = $(this).data('objid'); let searchResults = []; $("#whiletyping-solutions").find("a").each(function() { let is_selected = selectedId === $(this).data('objid'); searchResults.push({ objectId: $(this).data('objid'), contentType: $(this).data('contenttype'), category: $(this).data('category'), selected: is_selected }); }); $("#whiletyping-books").find("a").each(function() { let is_selected = selectedId === $(this).data('objid'); searchResults.push({ objectId: $(this).data('objid'), contentType: $(this).data('contenttype'), category: $(this).data('category'), selected: is_selected }); }); $.ajax({ url: autoCompleteSearchViewUrl, method: 'POST', data:{ csrfmiddlewaretoken: "mEv8rLXtVKV8Sxel0pfRZ4RzFiCLjJS5KZmUns7WFbY7bBV9aPxobAaY6lJUUmoe", query: $('#search-text').val(), searchObjects: JSON.stringify(searchResults) }, dataType: 'json', complete: function(data){ window.location.href = objectUrl; } }); }); });
    Why are mechanical brakes often used on cranes? | Numerade (2024)

    FAQs

    Why are mechanical brakes often used on cranes? | Numerade? ›

    The mechanical load

    mechanical load
    Mechanical load is the physical stress on a mechanical system or component leading to strain. Loads can be static or dynamic. Some loads are specified as part of the design criteria of a mechanical system.
    https://en.wikipedia.org › wiki › Mechanical_load
    brake is a key component of crane safety. It serves as a secondary braking mechanism of the crane hoist, controlling the lowering speeds of rated loads and preventing loads from free falling.

    Why are mechanical brakes often used on cranes? ›

    Why are mechanical brakes often used on cranes? Mechanical type brakes have an advantage in that they can hold a suspended load. What is the advantage of dynamic brakes over mechanical brakes? The advantage of dynamic braking is that there are no mechanical brake shoes to wear out.

    What is the purpose of a mechanical brake? ›

    Mechanical brakes function via force delivered to a body in rotary or linear motion, such as an axle, shaft, or wheel, to slow or stop motion. Mechanical brakes are often in an assembly with a mechanical clutch for engaging and disengaging shafts.

    What is the advantage of dynamic brakes over mechanical brakes? ›

    Friction wears down mechanical brake pads. But dynamic braking minimizes the use of mechanical brakes, thus reducing wear and tear and extending the life of brake components.

    What are the three methods that can be used to provide braking for a motor? ›

    Read on to learn about the three types of systems and when they're applicable.
    • Regenerative Braking. Regenerative braking is used when the driven load causes the DC motor to run at speeds higher than its no-load speed. ...
    • Dynamic Braking. ...
    • Plugging.
    Sep 28, 2020

    Why mechanical brakes are better than hydraulic? ›

    Advantages and disadvantages of mechanical disc brakes

    Compared to rim brakes, mechanical disc brakes provide reliable stopping power in a wide range of weather conditions, including rain and mud. They are also generally easier to maintain than hydraulic disc brakes, as they don't require bleeding.

    What is the purpose of the mechanical load brake? ›

    A mechanical load brake provides your crane hoist with the ability to manage/control the lowering speed of the crane hoist load. The load brake should also be able to hold the load on its own.

    What is mechanical advantage in brakes? ›

    In the case of bicycle brakes, the mechanical advantage of the system represents the ratio between the amount of force that presses the brake shoes against the rim and the amount of force that the rider's fingers have to apply to the brake levers to create this braking force.

    What is the main advantage of a mechanical drum brake? ›

    The main advantage of drum brakes is their low cost, in addition to being a very effective and long lasting system. Therefore, unlike disc brakes, the price of drum brake components is much lower than some of the components found in the market for disc brakes. That's a big difference between disc brake and drum brake.

    How do the brakes work on an overhead crane? ›

    When the brake is engaged, the friction material, such as brake pads or shoes, is pressed against the rotating drum or disc, generating frictional forces that counteract the crane's motion. The functionality of overhead crane brakes is closely linked to the type of braking mechanism used.

    What are the disadvantages of mechanical braking? ›

    The wear and friction caused by the working surface areas are quite severe. Thus, the longevity of a mechanical braking system between maintenance depends heavily on the type of material used to line the pad or shoe.

    How to differentiate between mechanical brake and hydraulic brake? ›

    With hydraulic brakes there is no brake cable involved in the process. Mechanical refers to when you pull the brake lever the brake cable is being pulled, which in return pulls the brake caliper that essentially pulls the brake pads into the rim.

    What are the different types of mechanical brakes? ›

    Types of Mechanical Brakes
    • Disc Brakes. Disc brakes use a rotor that is connected to a shaft. ...
    • Drum Brakes. Drum brakes are one of the oldest and most common types of mechanical brakes. ...
    • Band Brakes. A band brake works by having bands of material that tighten around a moving object. ...
    • Spring Brakes. ...
    • Cone Brakes.
    Feb 18, 2020

    What is the most common braking method? ›

    Hydraulic- Hydraulic brakes are the most common brake circuit in modern cars that utilize hydraulic (fluid) pressure to stop wheels in motion. The system uses two fluid-filled pistons and springs, one above the other.

    Which braking method is best? ›

    Threshold braking is the best strategy to adopt to gain maximum braking performance on tarmac. The point of maximum braking performance is found before the point of wheel lock, and when using threshold braking the driver attempts to try and keep the braking pressure just before this point.

    What is the most efficient braking technique? ›

    Utilize the Pivot Braking Technique

    The pivot technique is the easiest method to smoothly and consistently reduce your car's speed. Here's how to brake using the pivot technique: Place your right foot on the brake pedal with your heel on the car floor, so only the front part of your foot touches the pedal.

    What are the brakes used in cranes? ›

    Disc brakes are commonly used in overhead crane systems due to their exceptional stopping power and reliability. These brakes consist of a rotating disc attached to the crane shaft and a stationary brake caliper.

    What is one advantage of hydraulic brakes over mechanical brakes? ›

    Hydraulic disk brakes also provide more braking power because they have a greater contact area, which supports heat dissipation. They also rarely fail, making them reliable at high speeds and work better compared to mechanical brakes in wet and muddy conditions.

    References

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