四驅越野車車架及制動系統(tǒng)設計含6張CAD圖-原創(chuàng).zip
四驅越野車車架及制動系統(tǒng)設計含6張CAD圖-原創(chuàng).zip,越野車,車架,制動,系統(tǒng),設計,CAD,原創(chuàng)
液壓制動系統(tǒng)
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當踩下制動踏板，您希望該車輛停下。液壓制動踏板控制兩個部分。首先，在液壓作用下，由于采用細小的軟管或金屬線因此不必占用很大的空間。其次，液壓機構提供了一個很大的優(yōu)勢，由一個很小的力踩在制動踏板上，會產生很大的力作用于車輪上。制動踏板連接在充滿制動液的制動液壓缸的活塞上，液壓缸由活塞和油箱組成。
現(xiàn)代主缸其實是兩個獨立的腔體。這種結構稱之為雙回路系統(tǒng)，因為前腔連接到前制動器與后腔連接到后制動器。（有些車輛是對角連接）。兩個腔實際是分離的，允許緊急制動時一個系統(tǒng)失效另一個系統(tǒng)起作用。
整個液壓系統(tǒng)是從主缸到車輪都充滿制動液。當制動踏板放松時，活塞在總泵中移動，在整個液壓回路中產生壓力?；芈分谐錆M液壓力，強制輪（鼓式制動器）或（盤式制動器）壓迫制動蹄或制動盤。壓力壓迫制動蹄或制動片作用于制動鼓或制動盤最終是車輛停止。
此外，制動踏板控制一個燈的開關，剎車燈的踏板放松時，開關回到正常位置而燈滅。
每一個鼓式制動器包含兩個活塞，二個并排放置，向相反方向推動施加制動力。盤式制動器中，輪缸都是制動鉗（有的可能有多達4個或是1個 ）的一部分。所有活塞都使用某種類型的橡膠密封，防止液壓液泄漏出活塞，以及用橡膠密封防塵或污垢和水分進入輪缸。
當制動踏板被釋放，彈簧推動總泵活塞移動到總泵活塞在正常位置?；亓鏖y允許液體流向輪缸或流回制動總缸。當制動液流向制動輪缸，多余的液體回流，補償已被活塞移動距離的液壓油。液壓油若泄露也由回油閥回流。
所有雙回路制動系統(tǒng)使用一個開關來激活，并監(jiān)控液壓油的壓力。開關閥門位于警告位置安裝在主缸主閥門附近?；钊看螐那盎芈泛秃蠡芈分g循環(huán)。當結束制動是壓力是平衡的，活塞位置是穩(wěn)定的，但是當一個回路有泄漏，在更大的制動系統(tǒng)壓力下將迫使偏向活塞一方或另一方，關閉開關，就啟動警示燈. 點火開關起動發(fā)動機時或駐車制動時報警燈也是被激活的。
前盤，后鼓制動系統(tǒng)也有一個計量閥，以防止前，后制動器有制動間隙。用以確保前盤式制動器一般不會單獨使用，停止汽車。壓力控制閥也可以用來限制壓力，以防止在后輪制動中鎖定。
制動蹄和制動片使用相似材料。制動蹄或制動塊由金屬信號板和摩擦襯片組成。襯片是由粘結劑(被膠合)粘結或鉚接的。通常，鉚接的襯片效果比較好，但是粘結的襯片是更能充分表現(xiàn)摩擦材料的性能。
摩擦材料在不同的制造商中生產是不同的，并且大致的類型可被分為：石棉類，有機類，半金屬類，金屬類。在不同的類型中成分和成分的百分比是不同的。
一般來說，有機和非金屬石棉化合物是常用的，容易在電子設備中有好的表現(xiàn)。但是對于高溫操作來，他們可能不是您的耐用或山地駕駛的最佳的選擇。在許多情況下，這些襯片將比有些金屬化合物片更快速磨損，因此您經常得將替換他們。但是，當使用這些制動襯片時，電子設備將有更長的壽命。
半金屬剎車片或金屬化合物的表現(xiàn)因成分的不同而有所不同。一般來說，金屬含量越高，性能越好，摩擦材料的散熱性將越好。所以使它們更適合重型汽車使用，但是，金屬和半金屬為更容易發(fā)生嘯叫，在大多數(shù)情況下，金屬化合物比非金屬片更容易發(fā)生嘯叫。因此需要更經常更換襯片。
當你想確定什么類型的剎車片是適合你，請記住，在今天現(xiàn)代汽車制動系統(tǒng)是汽車的預期相匹配的表現(xiàn)性能之一。原始設備制造商從規(guī)格材質到剎車材料感覺并不能給你提供幫助。所以在你改變剎車材料前，先談談你的零件供應商，以幫助決定什么是最適合您的剎車片。
記住若你經常使用例如拖曳，停止并且頻繁駕駛，行駛在山路和賽跑也許都對性能材料有更高的要求因此需要你經常更換剎車片。
一些特殊的材料也用在剎車片中，其中有芳綸，碳材料。這些材料具有極其良好的剎車性能，山區(qū)駕駛或在賽場上駕駛都表現(xiàn)很好。耐磨性可能更勝于金屬材料，而許多的其他性能更像非金屬。
附 錄
Hydraulic Brake Systems
When you step on the brake pedal,you expect the vehicle to stop.The brake pedal operates a hydraulic that is used for two reasons.First,fluid under pressure can be carried to all parts of the vehicle by small hoses or metal lines without taking up a lot of room of causing routing problems.Second,the hydraulic fluid offers a great mechanical advantage-little foot pressure is required on the pedal,
but a great deal of pressure is generated at the wheels.The brake pedal is linked to a piston in the brake master cylinder containing a small piston and a fluid reservoir.
Modern master cylinders are actually two separate cylinders.Such a system is called a dual circuit,because the front cylinder is connected to the front brakes and the rear cylinder to the rear brakes.(Some vehicles are connected diagonally).
The two cylinders are actually separated,allowing for emergency stopping power should one part of the system fail.
The entire hydraulic system from the master cylinder to the wheels is full of hydraulic brake fluid.When the brake pedal is depressed,the piston in the master cylinder are forced to move,exerting tremendous force on the fluid in the lines.The fluid has nowhere to go,and forces the wheel cylinder pistons(drum brakes) or
caliper pistons(disc brakes) to exert pressure on the brake shoes or pads.The friction between the brake shoe and wheel drum or the brake pad and rotor (disc) slows the vehiche and eventually stops it.
Also attached to the brake pedal si a switch that lights the brake lights as the pedal is depressed.The lights stay on until the brake pedal is released and returns to its normal position.
Each wheel cylinder in a drum brake system contains two pistons,one at either end,which push outward in opposite directions.In disc brake systems,the wheel cylinders are part of the caliper (there can be as many as four or as few as one ).Whether disc or drum type,all pistons use some type of rubber seal to prevent leakage around the piston,and a rubber dust boot seals the outer of the wheel cylinders against dirt and moisture.
When the brake pedal is released,a spring pushes the master cylinder pistons back to their normal positions.Check valves in the master cylinder piston allow fluid to flow toward the wheel cylinders or calipers as the piston returns.Then as the brake shoe return springs pull the brake shoes back to the released position,excess fluid returns to the master cylinder through compensating ports,which have been uncovered as the pistons move back.Any fluid that has leaked from the system will also be replaced through the compensating ports.
All dual circuit brake systems use a switch to activate a light,warning of brake failure.The switch si located in a valve mounted near the master cylinder.A piston in the valve reveives pressure on each end from the front and rear brake circuits.When the pressures are balanced,the piston remains stationary,but when one circuit has a leak,greater pressure during the application of the brakes will force the piston to one side or the other,closing the switch and activating the warning light.The light can also be activated by the ignition switch during engine starting or by the parking brake.
Front disc,rear drum brake systems also have a metering valve to prevent the front disc brakes from engaging before the rear brakes have contacted the drums.This ensures that the front brakes will not normally be used alone to stop the vehicle.A proportioning valve is also used to limit pressure to the rear brakes to prevent rear wheel lock-up during hard braking.
Brake shoes and pads are constructed in a similar.The pad or shoe is composed of a metal backing plate and a priction lining.The lining is either bonded(glued) to the metal,or riveted.Generally,riveted linings provide superior performance,but good quality bonded linings are perfectly adequate.
4
ABSTRACT
A drive train for a four wheel drive vehicle including a front difforential engaged with a front drive shaft and front axles through a front differential gear set. The front differential includes a front bi-directional overrunning clutch that con-trols transmission of torque transfer between the front drive shaft and the front axles. A rear differential is engaged with rear axles and the transmission through a rear differential gear set. The rear differential includes a rear bi-directional over-running clutch that controls torque transfer between the trans-mission and the rear axles. The differentials are configured with a gear ratio that is within five percent of a l: 1 gear ratio.
TRUE FOUR WHEEL DRIVE SYSTEM FOR VEHICLE
RELATED APPLICATION
This application is related to and claims priority from U.S. Provisional Application 61/677,820, the disclosure of which is incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
The invention relates to drive systems and, more particularly, to an improved drive system designed to provide substantially true four wheel drive capability.
BACKGROUND
provide four wheel drive capability. Those systems are all designed to engage all four wheels but also allow a speed differential across the axle. However, many of those systems do not provide true four wheel drive where each wheel pro-vides substantially the same speed during all drive conditions. Instead, the systems permit some degree of slippage.
Current Four Wheel Drive Bi-Directional Overrun-ning Clutch Systems
I illustrates the drive system for a conventional four wheel drive vehicle with a front bi-directional over-rul111ing clutch. The drive system includes four wheels. The rear left wheel RLW is connected to a rear differential RD through a rear left axle RLA. The right rear wheel RRW is com1ected to the rear differential RD through a rear right axle RRA. The front left wheel FLW is col111ected to a front dif-ferential FD through a front left axle FLA. The front right wheel FRW is connected to the front differential FD through a front right axle FRA.mission T through a rear drive shaft RDS. The front differen-tial FD is connected to the transmission T through a front drive shaft EDS.
Straight Line Operation:
During straight line driving while the vehicle is in a four wheel on demand mode (i.e., four wheel drive engages only when needed) both rear wheels RLW, RRW are the primary drive wheels and are co1111ected through the rear differential RD to rotate at the same speed. In a non-slip condition of the rear wheels, the front drive shaft FDS is engaged to the front differential FD, but the front axles FLA, FRA are not engaged with the front differential. That is, the front axles FLA, FRA and front wheels FLW, FRW are gen-erally in an overrun condition such that the front differential FD is not driving the front axles FLA, FRA and, therefore, not transmitting any torque to the front wheels. This means that the front wheels FLW. FRW are free to rotate at their actual ground speeds.
In order for the front wheels to be engaged, the rear wheels must slip (break traction) or spin increase speed approximately 20% faster than the front wheels. While driv-ing in a straight line, once the rear wheels slip 20%, the overrunning condition in the front differential ED is over-come and both front axles are engaged. This results in the transmission T transmitting torque to the front wheels thru the front drive which is geared in a way that decreases the vehicles ground speed. When the ground speed has increased so as to cause the rear wheel speed to be rotating less than 20% faster than the ground speed, or the speed of the rear wheel has decreased so as to be rotating less than 20% faster than the ground speed, the front wheels will start to overrun again and no torque will be transmitted to the front wheels.
Turning Operation:
In a comer all four wheels are trying to rotate at different speeds, This is shown on the chart in FIG. 4 which depicts wheel revolutions vs. turning radius for all four wheels. For a vehicle with alocked rear axle or solid axle (i.e., an axle where the rear axles RLA, RRA are connected, either physically or through gearing, such that they always rotate at the same speed) the ground speed is dictated by the rear outside wheel due to vehicle dynamics (i.e., the rear outside wheel has to cover more circumferential distance than the rear inside wheel when turning around a common axis.) Since both rear wheels are rotating at the same speed and the rear outside wheel is the drive wheel the rear inside wheel is beginuing to scrub or drag on the ground. This can cause inefficiencies, turf wear and/or tire wear.
The primary reason conventional bi-directional ovemnming clutch four wheel drive systems have a 20% under drive is for turning. With the rear outside wheel dictat-ing ground speed the front inside wheel will go slower than the rear outside wheel as shown in FIG. 4. If there is no under drive the bi-directional oveITllllling clutch for the front inside axle would engage and begin to drive torque. This would cause the front inside wheel to travel at an incorrect speed and would create inefficiencies, turf wear, tire wear and, more importantly, torque steer.
As mentioned above, during a tum the rear outside wheel is dictating ground speed, the rear inside wheel is scrubbing or dragging, and the front wheels are overrunning. Referring to FIG. 5 which depicts the percentage difference between the front and rear wheel speeds versus the turning radius of a locked rear axle, once the rear outside wheel slips or spins a certain percentage, dictated by vehicle geometry and turning radius. the bi-directional overru1ming clutch con-trolling the transfer of torque to the front inside wheel will engage and drive torque through the front inside wheel At this time both rear wheels and the front inside wheel are driving torque and their speed is dictated by the drive line, not ground speed. The front outside wheel is still ovemmning allowing it to spin at the rotational speed dictated by ground speed and vehicle geometry. When both rear wheels and the front inside wheel slip a certain percentage, again dictated by vehicle geometry and the turning radius, the bidirectional clutch con-trolling torque transfer to the front outside wheel will engage and torque will be transmitted to all four wheels, even though three of the wheels would be slipping.
Wedging
The existing drive system is prone to a condition called wedging. Wedging occurs when torque is being driven through the bidirectional over-numing clutch and a rapid direction change occurs. This can cause the rollers in the clutch to be positioned or locked on the wrong side of the clutch profile preventing the output hubs from overru1ming. The effect causes the front drive to act like a solid axle, but with the 20% speed difference in the drive line it results in scrubbing of the front tires. This condition can cause exces-sive tire wear and turf wear. This also effects steering effort and stability of the vehicle. The vehicle will try to maintain a straight line due to the effect of the front drive acting like a solid axle.
Because of the wedging condition in the current systems precautions are put into place to help reduce wedging. One of these precautions is the use of a cut-off switch so that when the vehicle is shifted from the forward direction to the reverse direction so as to automatically disengage the bi-directional overrum1ing clutch (for example, shutting off the coil that is indexing the roll cage). This system also uses the cut-off switch when transitioning from the reverse direc-tion to the forward direction. Another way to reduce wedging is the use of a switch, when the brakes are applied, that will interrupt power to the 4 wheel drive system. Many other methods can be used to reduce wedging, but none are 100% percent effective with the 20% difference in drive line speeds.
Conventional Drive Systems:
A common conventional drive system would have the same vehicle layout as in FIG. 1, but the mechanisms in the front and rear differentials would be different. Most com-mon drive systems have an open differential with the ability to be locked into a solid axle in both the front and rear differen-tials. The drive line in a conventional system would also be using a drive line that is geared to a 1: 1 ratio
Straight Line Operation:
During straight line driving while the vehicle is in four wheel drive and all the axles are unlocked, all four wheels are rotating at the same speed. This is due to the drive line being geared at 1:1 ratio and the front and rear differen-tials are being driven at the same speed and no differentiation is needed across the axles. This is also the case when any or both of the front and rear differentials are in a locked position creating a solid axle.
Turning operation:
Conventional four wheel drive systems will nor-mally have the rear differential locked and the front drive will be in the open state until the solid axle mode is selected by the user. During turning with a solid axle in the rear differential and an open differential in the front, only one tire is turning at the correct ground speed. Due to vehicle dynamics the rear outside wheel is considered the drive wheel and is turning at ground speed. The inside rear wheel is being driven at the same speed as the rear outside, but the ground speed is slower. This causes the inside rear wheel to scrub or slip during a tum. (0023] Since the two front wheels are connected to an open differential, they are allowed to differentiate across the axle, However, the differential is being driven at an incorrect speed. That is, the front open differential takes the input speed and averages it across the axle. In a normal non slip condition the average speed across the axle is centered about the middle of he vehicle. Since the rear outside wheel is traveling at a different speed ( or arc) than the average of the two front wheels, both front wheels are scrubbing when in a tum caus-ing un-needed drive line torque or drive line bind.
Once the operator selects the solid axle mode of the vehicle, both front wheels are locked together and they now rotate at the same speed. When turning, the outside front wheel is going slower than what ground speed dictates, thus causing the wheel to scrub. At the same time the inside front wheel is going faster than the ground speed dictates causing it to, likewise, scrub.
Due to the wheels being driven at the wrong speeds in a comer, conventional drive systems are not very efficient. They cause severe turf damage or wear due to the tires scrub-bing. They also cause tire wear due to the scrubbing. The tires being driven at the wrong speeds also cause issues with steer-ing and turning performance of the vehicle. The difference between ground and actual wheel speed results in the wheels trying to straighten the vehicle out. This cause's increased wear in steering components, as well as rider fatigue since increased input is needed to maintain the vehicle in the tum. Many manufacturers have added power steering to try to minimize operator input when cornering because of the four wheel drive operations.
A need therefore exists for an improved four wheel drive system that incorporates bi-directional overrunning clutches in a drive system that minimizes scrubbing in all wheels while permitting 1.1 or near 1: 1 gear ratio between the front and rear axles.
SUMMARY OF THE INVENTION
The present invention is directed to drive train for a four wheel drive vehicle. The drive train includes a front drive shaft connected to a transmission. Two front axles with each axle connected to a corresponding front wheel. A front dif-ferential is engaged with the front drive shaft and the front axles through a front differential gear set. The front differen-tial includes a front bi-directional overrunning clutch that controls transmission of torque transfer between the front drive shaft and the front axles.
The front bi-directional ovemmning clutch includes a front clutch housing connected to the front drive shaft so as to be rotatable by the front drive shaft, the front clutch hous-ing including an inner cam surface. A front roller assembly is located inside the front clutch housing and adjacent to the cam surface. The front roller assembly includes a roll cage with a plurality of rollers arranged in two sets within slots formed in the roll cage, the rollers are rotatable inside the slots. A plurality of springs are arranged in the roll cage to position the rollers within the slots. The roll cage is rotatable within the front clutch housing. (0029] Two front hub are located in the front clutch hous-ing. Each hub is positioned radially inward from a set of the rollers located between an outer surface of the front hub and the im1er cam surface. Each front hub is engaged with an axial end of one of the front axles so as to rotate in combination with the axle. The front hubs are independently rotatable within the roll cage and the front clutch housing.
A front engagement control assembly is located within the housing and controls engagement and disengage-ment of the front bi-directional overrunning clutch. The front engagement control assembly includes an electromechanical device that is controllable for impeding rotation of the roll cage relative to the front clutch housing so as to index the roll cage relative to the front clutch housing.
When the engagement control assembly is activated and the roll cage is indexed relative to the clutch housing, the front bi-directional overrunning clutch is configured to trans-mit torque from the front drive shaft to the front axles when the front clutch housing is rotating faster than the front axles. Also, when the vehicle is traveling straight the front differen-tial is configured to begin to transmit torque from the front drive shaft to the front axles at a first speed.
The gear train including two rear axles, each axle com1ected to a corresponding rear wheel. A rear differential is engaged with the rear axles and the transmission through a rear differential gear set. The rear differential including a rear differential housing and a rear bi-directional overrunning clutch that controls torque transfer between the transmission and the rear axles.
The rear bi-directional overrunning clutch includes a rear clutch housing located within the rear differential !mus-ing and rotatable by the transmission, the rear clutch housing including an inner cam surface. A rear roller assembly is located inside the rear clutch housing and adjacent to the cam surface. The rear roller assembly includes a roll cage with a plurality of rollers arranged in two sets within slots formed in the roll cage. The rollers are rotatable inside the slots. A plurality of springs are arranged so as to position the rollers within the slots. The roll cage is rotatable within the rear clutch housing.
Two rear hubs are located in the rear clutch housing. Each hub is positioned radially inward from a set of the rollers located between an outer surface of the rear hub and the im1er cam surface. Each rear hub is engaged with an axial end of one of the rear axles so as to rotate in combination with the axle. The rear hubs are independently rotatable within the roll cage and the rear clutch housing.
The rollers in each set of the rear roller assembly are adapted to wedgingly engage the corresponding rear hub to the rear clutch housing when one of either the rear hub or rear clutch housing is rotating faster than the other so as to trans-mit torque from whichever is faster to whichever is slower.
The differentials are configured such that when the vehicle is traveling straight and the rear differential is trans-mitting torque to the rear axles. The rear differential is con-figured to rotate the rear axles at a second speed, and where the difference between the first speed and the second speed is five percent or less. In one preferred embodiment, the differ-ence between the first speed and the second speed is less than about three percent. In another embodiment there is substan-tially no difference between the first speed and the second speed.
In one embodiment, the front bi-directional over-running clutch includes an armature plate that is engaged or connected with the front roll cage such that the armature plate rotates with the roll cage. The front engagement control assembly impedes rotation of the roll cage relative to the front clutch housing by engaging the amiature plate so as to index the roll cage relative to the clutch housing.
Preferably the hubs are substantially coaxially aligned with each other within the housing. and are adapted to rotate about a common axis within the housing.
In one embodiment, the rear differential is part of a transaxle which is engaged with the transmission. 。
In another embodiment the front differential is part of a transaxle which is engaged with the transmission.
The foregoing and other features of the invention and advantages of the present invention will become more apparent in light of the following detailed description of the preferred embodiments, as illustrated in the accompanying figures. As will be realized, the invention is capable of modi-fications in various respects, all without departing from the invention. Accordingly, the drawings and the description are to be regarded as illustrative in nature, and not as restrictive.
摘要
一種用于四輪驅動車輛的傳動系統(tǒng)，包括與前驅動軸接合的前差速器和通過前差速齒輪組的前軸。 前差速器包括前雙向超越離合器，其控制前驅動軸和前軸之間的扭矩傳遞的傳遞。 后差速器通過后差速齒輪組與后軸和變速器接合。 后差速器包括控制變速器和后軸之間的扭矩傳遞的后雙向超越離合器。差速器構造成具有百分之五內1：1的齒輪比誤差比。
真正的四輪驅動系統(tǒng)車輛
相關申請
本申請與美國臨時申請61 / 677,820相關并要求其優(yōu)先權，其公開內容通過引用整體并入本文。
本發(fā)明涉及驅動系統(tǒng)，更具體地，涉及一種設計成提供基本上真實的四輪驅動能力的改進的驅動系統(tǒng)。
背景
提供四輪驅動能力。 這些系統(tǒng)都被設計成接合所有四個車輪，但也允許在車軸上有速度差。 然而，這些系統(tǒng)中的許多不提供真正的四輪驅動，其中每個輪在所有驅動條件期間提供基本相同的速度。 相反，系統(tǒng)允許一定程度的滑動。
正確的四輪驅動雙向超越離合器系統(tǒng)
圖1示出了用于具有前部雙向超越離合器的常規(guī)四輪驅動車輛的驅動系統(tǒng)。 驅動系統(tǒng)包括四個輪子。 后左輪RLW通過后左輪軸RLA連接到后差速器RD。 右后輪RRW通過右后輪RRA連接到后差速器RD。 前左輪FLW通過左前車軸FLA與前差速器FD連接。 右前輪FRW經由右前輪FRA與前差速器FD連接。
單元T通過后傳動軸RDS。 前差速器FD通過前驅動軸EDS連接到變速器T.
直線操作
在車輛處于四輪按需模式（即，四輪驅動僅在需要時接合）的直線行駛期間，兩個后輪RLW，RRW都是主驅動輪，并且通過后差速器RD聯(lián)接以旋轉 以相同的速度。 在后輪的防滑狀態(tài)下，前驅動軸FDS接合到前差速器FD，但是前軸FLA，F(xiàn)RA不與前差速器接合。 也就是說，前軸FLA，F(xiàn)RA和前輪FLW，F(xiàn)RW通常處于超速狀態(tài)，使得前差速器FD不驅動前軸FLA，F(xiàn)RA，因此不向前輪傳遞任何扭矩。 這意味著前輪FLW。 FRW可以以其實際地速度自由旋轉。
為了使前輪接合，后輪必須滑動（斷開牽引）或旋轉增加速度比前輪快大約20％。 當在直線上行駛時，一旦后輪滑動20％，則克服前差速器ED中的超速狀況，并且兩個前軸接合。 這導致變速器T通過以減小車輛地速的方式來使變速的前驅動器將扭矩傳遞到前輪。 當?shù)厮僭黾右灾率购筝喫俣缺鹊厮俚男D小于20％，或者后輪的速度已經減小以便比地速更快地旋轉小于20％時 ，前輪將再次開始超速，并且沒有扭矩將被傳遞到前輪。
轉向操作：
在角落中，所有四個輪子都試圖以不同的速度旋轉。這在圖1中的圖表上示出。 圖4示出了所有四個車輪的車輪轉數(shù)對轉彎半徑。 對于具有鎖定的后軸或實心軸（即，其中后軸RLA，RRA被物理連接或通過齒輪連接，使得它們總是以相同的速度旋轉的軸）的車輛，地速由后外側 由于車輛動力學（即，當圍繞公共軸線轉動時，后外輪必須覆蓋比后內輪更多的圓周距離）。由于兩個后輪以相同的速度旋轉，并且后外輪是驅動輪 后內側輪開始在地面上擦洗或拖曳。 這可能導致效率低下，草皮磨損和/或輪胎磨損。
主要原因是傳統(tǒng)的雙向四通離合器四輪驅動系統(tǒng)力的20%用于轉向。 由于后外輪確定地速，前內輪將比后外輪慢，如圖3所示。 如果沒有低于驅動，用于前內軸的雙向偏心離合器將接合并開始驅動扭矩。 這將導致前內側車輪以不正確的速度行駛，并且將產生低效率，草皮磨損，輪胎磨損，并且更重要的是，扭矩轉向。
如上所述，在轉彎期間，后外輪輪流地面速度，后內輪是擦洗或拖曳，并且前輪是超速的。參考圖1。圖5示出了一旦后外輪滑動或旋轉一定百分比（由車輛幾何形狀和轉彎半徑決定）時，前后車輪速度相對于鎖定后車軸的轉動半徑的百分比差異?？刂频角皟容喌霓D矩傳遞的雙向超越離合器將接合并通過前內輪驅動轉矩。此時，后輪和前內輪都是驅動轉矩，并且它們的速度由驅動線決定，不是地速。前外輪仍然是超速的，允許其以由地速和車輛幾何形狀決定的旋轉速度旋轉。當兩個后輪和前內輪滑動一定百分比，再次由車輛幾何形狀和轉彎半徑決定時，控制到前外輪的扭矩傳遞的雙向離合器將接合，并且扭矩將被傳遞到所有四個車輪中，即使其中的三個車輪將滑動。
楔入
現(xiàn)有的驅動系統(tǒng)傾向于稱為楔入的狀態(tài)。 當扭矩通過雙向超越離合器被驅動并且發(fā)生快速方向改變時，發(fā)生楔入。 這可能導致離合器中的輥定位或鎖定在離合器輪廓的錯誤側上，從而防止輸出輪轂過度磨損。 該效果使得前驅動器像實心軸一樣起作用，但是在驅動線中具有20％的速度差，這導致前輪胎的擦洗。 這種情況可能導致過度的輪胎磨損和草皮磨損。 這也影響車輛的轉向力和穩(wěn)定性。 由于前驅動器像實心軸一樣作用的效果，車輛將試圖保持直線。
由于當前系統(tǒng)中的楔入條件，采取預防措施以幫助減少楔入。 這些預防措施之一是使用切斷開關，使得當車輛從正向轉換到相反方向時，以便自動地脫離雙向旋轉離合器（例如，關閉正在分度的線圈 滾動保持架）。 當從反方向轉換到正方向時，該系統(tǒng)也使用截止開關。 減少楔入的另一種方式是在應用制動器時使用開關，其將中斷對四輪驅動系統(tǒng)的供電。 許多其他方法可以用于減少楔入，但是沒有一種方法對于驅動線速度的20％差異是100％有效的。
傳統(tǒng)驅動系統(tǒng)：
常見的傳統(tǒng)驅動系統(tǒng)將具有與圖1中相同的車輛布局，但前差速器和后差速器中的機構將是不同的。最常見的驅動系統(tǒng)具有打開的差速器，其具有鎖定到固體中的能力 在傳統(tǒng)系統(tǒng)中的驅動線也將使用傳動比為1：1比率的驅動線
直線操作：
在車輛處于四輪驅動并且所有車軸都被解鎖的直線行駛期間，所有四個車輪以相同的速度旋轉，這是由于驅動線以1:1的比率傳動，并且前部和 后差速器以相同的速度被驅動并且不需要跨越軸的差異，當前差速器和后差速器中的任何一個或兩者處于產生實心軸的鎖定位置時也是
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