【正文】 s plan contribution must meet certain minimum standards as to employee participation and vesting and employer funding. ERISA also approved the use of individual retirement accounts (IRAs) to encourage taxdeferred retirement savings by individuals. The Economic Recovery Tax Act of 1981 (ERTA) provided the largest tax cut up to that time, reducing the maximum individual rate from 70 percent to 50 percent (Pub. L. No. 9734, Aug. 13, 1981, 95 Stat. 172). The most sweeping tax changes since world war ii were enacted in the Tax Reform Act of 1986. This bill was signed into law by President ronald reagan and was designed to equalize the tax treatment of various assets, eliminate tax shelters, and lower marginal rates. Conservatives wanted the act to provide a single, low tax rate that could be applied to everyone. Although this single, flat rate was not included in the final bill, tax rates were reduced to 15 percent on the first $17,850 of ine for singles and $29,750 for married couples, and set at 28 to 33 percent on remaining ine. Many deductions were repealed, such as a deduction available to twoine married couples that had been used to avoid the marriage penalty (a greater tax liability incurred when two persons filed their ine tax return as a married couple rather than as individuals). Although the personal exemption exclusion was increased, an exemption for elderly and blind persons who itemize deductions was repealed. In addition, a special capital gains rate was repealed, as was an investment tax credit that had been introduced in 1962 by President john f. kennedy. The Omnibus Budget Reconciliation Act of 1993, the first budget and tax act enacted during the Clinton administration, was vigorously debated, and passed with only the minimum number of necessary votes. This law provided for ine tax rates of 15, 28, 31, 36, and percent on varying levels of ine and for the taxation of social security ine if the taxpayer receives other ine over a certain level. In 2022 Congress enacted a major ine tax cut at the urging of President gee w. bush. Over the course of 11 years the law reduces marginal ine tax rates across all levels of ine. The 36 percent rate will be lowered to 33 percent, the 31 percent rate to 28 percent, the 28 percent rate to 25 percent. In addition, a new bottom 陜西鐵路工程職業(yè)技術(shù)學(xué)院畢業(yè)設(shè)計(jì)（論文） 21 10 percent rate was created. Since the early 1980s, a flatrate tax system rather than the graduated bracketed method has been proposed. (The graduated bracketed method is the one that has been used since graduated taxes were introduced: the percentage of tax differs based on the amount of taxable ine.) The flatrate system would impose one rate, such as 20 percent, on all ine and would eliminate special deductions, credits, and exclusions. Despite firm support by some, the flatrate tax has not been adopted in the United States. Regardless of the changes made by legislators since 1913, the basic formula for puting the amount of tax owed has remained basically the same. To determine the amount of ine tax owed, certain deductions are taken from an individual39。 loan amp。感謝三年來一起學(xué)習(xí)、生活的同學(xué)們，在他們的幫助下，我順利的解決了生活中遇到的各種困難。老師們課堂上的激情洋溢，課堂下的諄諄教誨。 陜西鐵路工程職業(yè)技術(shù)學(xué)院畢業(yè)設(shè)計(jì)（論文） 17 致 謝 我的畢業(yè)論文是在左維琦老師的精心指導(dǎo)和大 力支持下完成的，左老師淵博的專業(yè)知識，嚴(yán)謹(jǐn)?shù)闹螌W(xué)態(tài)度，精益求精的工作作風(fēng)，誨人不倦的高尚師德，嚴(yán)以律己、寬以待人的崇高風(fēng)范，樸實(shí)無華、平易近人的人格魅力對我影響深遠(yuǎn)。當(dāng)定型鉆車不能適應(yīng)工程要求 (主要是工作斷面、鑿巖生產(chǎn)率和臂數(shù)不足 )時(shí)，則采用專門設(shè)計(jì)的非定型鉆車。 陜西鐵路工程職業(yè)技術(shù)學(xué)院畢業(yè)設(shè)計(jì)（論文） 16 第 5 章 結(jié)論與建議 目前世界上各大公司液壓鑿巖臺車的鉆臂、推進(jìn)器和操縱系統(tǒng)等主要部件都已實(shí)現(xiàn)標(biāo)準(zhǔn)化和系列化。 出現(xiàn)非正常情況的處置和報(bào)告 1．當(dāng)設(shè)備在運(yùn)行中出現(xiàn)著火時(shí)，司機(jī)要在最短的時(shí)間內(nèi)將車停穩(wěn)，盡快切斷動力電源，并用就近的滅火器進(jìn)行滅火，火勢較大，不能撲滅時(shí)要立即報(bào)告調(diào)度室或報(bào)火警。 4．支起千斤支腿。 3．鑿眼時(shí)，臺車前后不得有人逗留。 7．打開車頂工作燈，啟動工作油泵。用電筆測試檢查電纜和車體是否存在漏電，有漏電必須進(jìn)行處理。人工拖拽時(shí)，電纜盤手柄要放在“ out”位置，電纜盤轉(zhuǎn)動，電纜放出。嚴(yán)禁在行駛中掛倒退檔位。 4．收回支腿。 臺車的起步與停止 1．確保電纜盤和配電柜連接牢靠。 4．檢查液壓系統(tǒng)各操作手柄是否完好，對系統(tǒng)的操作是否到位，有無氣阻或滯后現(xiàn)象。根據(jù)指示燈檢查制動壓力， 制動欠壓時(shí)指示燈亮；根據(jù)指示燈檢查傳動系統(tǒng)油溫；根據(jù)指示燈檢查發(fā)動機(jī)機(jī)油壓力，欠壓時(shí)指示燈亮；檢查電瓶電壓；檢查發(fā)動機(jī)溫度。發(fā)動機(jī)太冷要預(yù)熱，轉(zhuǎn)動鑰匙到預(yù)熱位置，一般預(yù)熱時(shí)間為 15— 20 秒，最長不得超過 60 秒。 發(fā)動機(jī)啟動 1．啟動發(fā)動機(jī)前要確認(rèn)手制動按鈕在制動位置；方向選擇旋鈕在中間位置；熄火控制桿復(fù)位；各控制手柄、控制裝置在中間位置或初始位置。 9．檢查工作機(jī)構(gòu)液壓系統(tǒng)膠管有無破損，膠管捆扎、吊掛是否整齊、牢靠。檢查輪胎螺絲，有松動或缺損的要立即處理。 3．檢查消防器材、三角掩木是否完備，檢查滅火器壓力表指針是否在工作區(qū)域內(nèi)。 10．主電路系統(tǒng) —— 檢查電纜情況，檢查電控柜。 6．操 作室 —— 檢查頂燈，檢查工作燈，檢查雨刷器狀態(tài)，潤滑門合頁，檢查玻璃清洗液位，檢查空調(diào)過濾濾芯。 2．鉆臂 —— 檢查管子和聯(lián)結(jié)狀態(tài)，潤滑注油點(diǎn)，檢查電纜狀態(tài)。確保根據(jù)液壓圖正確聯(lián)接。油噴射出來易發(fā)生火災(zāi)。對自己不熟悉的東西要慎重。 3．高壓油噴射時(shí)能穿透皮膚造成嚴(yán)重的傷害。確保在松開接頭，堵頭或液壓閥等部件前油路已卸壓。 4．在更換傳感器及傳感器電纜時(shí)必須先關(guān)掉液壓及主電源，同時(shí)在聯(lián)接電纜接頭時(shí)，必須按照原安裝要求進(jìn)行安裝，避免燒壞傳感器模塊及控制系統(tǒng)。請注意緊急停按鈕被按下時(shí)照明燈仍然亮，并且設(shè)備并未斷電。系統(tǒng)壓力值不能超過工廠規(guī)定值，增加壓力值并不能增加臺車的性能。 2． 參照廠家規(guī)定，了解沒備設(shè)計(jì)思想和熟悉其工作原理，嚴(yán)格按照修理工藝規(guī)程進(jìn)行。 陜西鐵路工程職業(yè)技術(shù)學(xué)院畢業(yè)設(shè)計(jì)（論文） 10 第 3 章 XE3D 液壓鑿巖臺車維護(hù)保養(yǎng) 維護(hù)保養(yǎng)的安全注意事項(xiàng) 1．只能由經(jīng)培訓(xùn)的認(rèn)證人員對臺車進(jìn)行維護(hù)，調(diào)試，保養(yǎng)。主要原因是大臂與鉆桿存在尺寸差異，當(dāng)大臂靠近巖面時(shí)，鉆桿靠近內(nèi)側(cè)，與上一循環(huán)搭接處就會存在錯臺。當(dāng)出現(xiàn)這種情況時(shí)，操作手應(yīng)當(dāng)進(jìn)行人工干預(yù)鉆孔。 5 在．臺車自動鉆孔過程中，操作手應(yīng)時(shí)刻關(guān)注鉆臂的移動情況，避免與凸出巖石產(chǎn)生碰撞，損壞設(shè)備。 液壓鑿巖臺車施工過程控制 1．利用鉆臂進(jìn)行鉆孔定位時(shí)，應(yīng)盡量選擇凹凸適中的位置進(jìn)行定位，以 免造成凸出部分因鉆桿長度不夠而造成鉆孔深度不夠，影響爆破效果。 3．臺車在運(yùn)行中出現(xiàn)熄火故障，使制動、轉(zhuǎn)向失靈 或誤操作等而造成溜車、撞車等車輛傷害事故。如情況嚴(yán)重，應(yīng)立即停機(jī)，并通知相關(guān)部門。 2．操作人員必 須戴安全帽，戴好防塵口罩，穿好工作服，扎好袖口。 3．關(guān)上電源開關(guān)后，方可檢查電氣系統(tǒng)。 4．操作人員因故暫離臺車而停止作業(yè)時(shí)，也應(yīng)切斷臺車電源。 停車作業(yè) 1．不能將臺車停放在軟地基處，以及側(cè)壁和頂部有落石或巖崩危險(xiǎn)的地方。 7．操作升降平臺動作時(shí)，一定要用手勢或信號提醒下方作業(yè)人員注意，隨時(shí)查看下方的臂與導(dǎo)桿的位置是否正確。 5．在鑿巖作業(yè)和升降平臺上作業(yè)時(shí)，嚴(yán)禁移動機(jī)體。 鑿巖及其它作業(yè) 1．進(jìn)入鑿巖作業(yè)之前，應(yīng)清除作業(yè)面上的浮石，特別是在鑿鉆錨桿孔時(shí)更應(yīng)注意安全。由于臺車的機(jī)體很長，即使轉(zhuǎn)向角不大、機(jī)體的前端與尾端也會極度擺動，故操作時(shí)要特別慎重。 行走作業(yè) 1．降下升降平臺，倒回滑動工作臺，縮回臂架，將導(dǎo)桿擺成水平，鑿巖機(jī)保持在始動位置，縮回支腿，方能行走。 Atlas Copco 鑿巖臺車液壓系統(tǒng)元件的布置結(jié)構(gòu)緊湊，反復(fù)拆卸是很費(fèi)勁的事，采用這種方法