คำตอบที่ 1
       ดูสภาพการใช้งานเป็นหลักซิครับ ถ้างานของคุณต้องขึ้นทางลาดชันอยู่บ่อยๆ และเราเห็นว่าดิฟท์หน้าทำงานได้ดีกว่าถึงแม้จะต้องคอยมาปลดล็อค แต่มันก็ได้ผลไม่ใช่เหรอครับ? เน้นการใช้งานเป็นหลักครับไม่ต้องแต่งตามเพื่อน

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คำตอบที่ 2
       ใช่ครับ เท่าที่อ่านกระทู้จากต่างประเทศ
Lock หน้าจะมีประโยชน์มากกว่าครับ
แต่ถ้าเนินชันแต่ผิวทางเรียบ หลังน่าจะดีกว่า
แต่ชันและมีหินหรือต้องปีนป่ายด้วย หน้าดีกว่าแน่นอนครับ

The installation of a diff lock on your vehicle somehow adds that mystical quality to your 4WD standing. Some people choose not to let on their ‘secret’ and attempt to cultivate a driving reputation of ‘4WD legend’ status. Others boast to all and sundry of their installation and then fail to deliver the magical performance now expected. But really, what is all the hype about diff locks, and is it deserved?

To set the record straight, the diff lock fitted as standard equipment to all permanent 4WD’s does nothing more than make it the same as the "lesser" part-time 4WD’s when in four wheel drive. A permanent 4WD has a centre differential whereas a part-time 4WD does not. The diff lock only locks the centre diff and has nothing to do with the differential on the front and rear axles.

The diff lock most 4WDrivers talk about, and the one refered to in this article, is when its fitted to the front or rear axle of the vehicle. Its here that the mystic begins. A ‘normal’ differential transmits drive to both wheels equally when they receive equal traction, but when one wheel loses traction, the diff actually transmits more drive to that wheel. Hence you can become stuck in 2WD with only one wheel bogged. Similairly, when in 4WD you can be bogged with one front and one rear wheel without traction. So your 4WD is really only a 2WD, with one front and one rear wheel providing all forward momentum.

To overcome this limitation many vehicle manufacturers fit a limited slip differential (LSD) to the rear of most new 4WDs. A LSD is an improvement to the open differential but, as its name implies, it only provides limited drive to the wheel that has traction. To appreciate just how ‘limited’ the slip is, try the following test. With a vehicle fitted with a rear LSD, place an axle stand to lift one of its rear wheels off the ground and then chock both front wheels with a brick. The LSD will not provide enough torque to drive the vehicle over the brick (vehicle obviously in 2WD). If a diff lock was fitted then the vehicle would drive forward easily.

In many offroad circumstances the traction avaliable to the rear wheels is similair and the LSD can control any wheelspin. However as soon as there is a large difference in traction ie. one wheel off the ground, there is no way a LSD will have any beneficial effect. The reason the diff lock is so effective is that it provides equal drive to each wheel, regardless of traction. When a diff lock is fitted to both front and rear, a vehicle has to loose traction to all four wheels before it stops.

Diff locks obviously provide more traction but their effect is more dramatic in certain terrain types. The greatest improvement comes on deeply gouged rocky tracks where there is plenty of traction and the rough ground results in opposite wheels not touching the track. The least improvement comes in smooth slippery tracks where all wheels have roughly the same weight on them but there is simply not enough traction. It is quite common in these circumstances for all four wheels to spin even when diff locks are not fitted.

A diff lock is not some magical device that can create more traction for your vehicle, all it can do is make avaliable the same amount of torque to each wheel. In simplistic terms, a four wheel drive vehicle is only a 2WD whereas a front and rear diff locked vehicle is a true 4WD. In pratical terms, a vehicle with front and rear diff locks will go places that no ordinary 4WD can.

So now you can see why to fit a diff lock, but what type? And if fitting to only one diff, is a front or rear fitment more effective. First of all, its better to explain the different types of lockers commonly avaliable. The three most common brands of diff locks comprise of essentially two different types. The Detroit Locker and the Lock Right are an automatic locker that are always in operation. They work by leaving the diff locked and automatically unlocking it when required. Without getting technical, they work by transmitting drive equally to both wheels but allow a wheel to turn faster than driven speed, such as required when cornering. The ARB diff lock is operated by a switch when required and locks the diff completely. It does not allow any difference in wheel speed on the same axle.

The advantage of the automatic lockers is that they allow one wheel to overspeed, thus allowing easier cornering. When fitted to the front diff, this allows steering control to be easily maintained whereas a locked diff tends to go straight ahead. Proponents of locking diffs point out that the diff can be turned off to allow steering control or that it should only be used when traction is so poor it makes no difference to steering. In practice, it is a definite advantage to maintain steering control. However, an automatic locker should not be fitted to the front diff of permanent four wheel drives as it has a noticable effect on steering when on reasonable traction surfaces. When a part-time 4WD is in 2WD there is no effect what so ever on the steering from an auto diff lock. A permanent 4WD’s only option for the front diff is an ARB locker.

The rear axle can have either an automatic locker or ARB locker regardless of being a permanent or part-time 4WD. The overspeed advantages of an automatic locker are minimal on a rear axle fitting as far as steering effect are concerned. The biggest difference is that an automatic locker is ALWAYS working whether in 2 or 4 wheel drive or on dirt or bitumen. In practice, this results in being able to go most places in 2WD whereas 4WD would have been required previously. It is still good practice however to use 4WD as soon as pratical when on dirt as it minimises the impact on the enviroment.

An ARB locker should only be used in the dirt when traction is so poor that one wheel is close to loosing traction, otherwise axle windup may occur if used on good traction surfaces. At this point, it may seem that automatic lockers have it all over the ARB locker but its not quite that cut and dried. Even when fitted to the rear there is an effect on the vehicle by an auto locker as it cams in and out. It is more noticable in short wheel based petrol powered vehicles than in long wheel based diesel vehicles, where the effect is minimal. It occurs mainly when getting off and on the gas in corners and has a lot to do with driving style. It shows up as an audible clicking from the rear and in some circumstances can have a slight understeer effect. Once an auto locker is fitted to the rear this effect will always be present to a varying degree. Most drivers are unaware of this effect, bit if its of any concern you can adapt your driving style to minimise its impact. An ARB locker is only switched on as required so there is no effect during on-road driving.

So now your aware of the differences between the types of lockers avaliable, which is the best place to fit a single diff lock, front or rear? This is actually a loaded question as it depends on the type of terrain and your vehicle type, but in a nutshell I believe the front is the best place. This is especially so for independent front suspension vehicles which easily lift a wheel even on modest terrain. Additionally, most vehicles these days already have a rear LSD so why fit a locker to the rear and leave the front diff open? Its a better option to fit the locker to the front and leave the LSD in place. When the vehicle has open diffs back and front there are still advantages for a front fitment. When in sand or mud the fitting of a locker to the front will have a greater effect. If hill climbs are your main speciality then a rear fitment may be a better choice as there is a significant weight transfer to the rear axle when going uphill. However if the hillclimb requires large rocks, gullies or shelves to be driven over, then a front locker will drive over the obstacle rather than being pushed up it from behind. As you can see, there is no right or wrong answer, just different choices depending on individual factors.

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คำตอบที่ 3
      

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คำตอบที่ 4
       ขอบคุณพี่ ping มากครับ ท่านใดมี ความรู้ เรี่องดิกฟ์ ขอเชิญ แบ่งปักความรู้ได้เลยครับ

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คำตอบที่ 5
       อีกมุมของ Lock หน้าครับ
การเลี้ยวจะมีปัญหา แรงต้านเยอะ
ปีนป่ายหิน ถ้าล้อตรง lock หน้าได้ ถ้าปีนหินมีเลี้ยว ห้ามใช้
ลงเนินให้ lock หน้า+หลัง(ถ้ามี)ไม่ควรแตะเบรก

Driving with Lockers: Is Parallel Power Really Easier? by Bill Burke
Although both my D-90 and my Range Rover have lockers, I want those that I am training to understand how to drive without using, or actually getting used to, lockers. Granted ARB lockers are great; switch them on whenever you need them and the rest of the time they are off!

I have always taught that it's best to learn how to negotiate the terrain without lockers so you get the finesse of 4-wheeling down.
Understand the dynamics of the vehicle and its handling characteristics on- and off-highway, then start to add the goodies. Yes, I own Air Lockers now but I cut my teeth on posi-traction and Detroit Lockers. Try driving Detroit's front and rear with 35's and no power steering!

While you negotiate rough terrain, the suspension and your "line" will not always allow you to have smooth contact with the ground. At some point, the tire will catch air or lose full proximity with the ground, causing the tire to spin. Remember Murphy's Law, the tire with the least amount of traction gets the most amount of power. You will hit moguls, come off rock ledges with two tires and attempt hills with very loose soil. This is where lockers really come in handy.

Once you've purchased a set of lockers and had them installed, here is a short course on how and when to use them. Whether you have air, electric or mechanical lockers, limited slip, posi-traction or whatever, the techniques are generally the same.

First: be careful on side angled (off-camber) hill sides; i.e., the vehicle is traveling on a side slope. If it is mucky, icy, snowy or any other type of slippery-slidey side slopey slope, use open diff, if possible. Lockers will tend to "walk" you sideways down slope. This is because both wheels are rotating at the same speed. If one wheel is "static" and the other is rotating, the static one will act as an anchor or stabilizer that will keep the rig from slipping sideways. When on these side slopes, let the vehicle idle across, giving the tires a chance to dig in and get the best traction.

Second: when going up hills or any incline, aim straight up. The weight shift to the rear will give you added traction so the locker in the rear is advantageous. WATCH OUT for the front end, though! The tires will have a tendency to catch ledges and occasionally loose soil and "walk" the front end around either left or right, causing the rig to get sideways on a hill. Then if you PANIC, give it gas, and don't come out of lock, you could roll over.

I usually get lined up for the ascent, approach cautiously, engage the rear locker and start the climb. Depending on the terrain, rock ledges, sand, loose granite, mud, etc., I will then engage the front locker once I feel control of the steering and front end traction have been attained (gut feeling!). About halfway up the incline, I'll engage the front locker. If you don't have air lockers, be careful of the front end walking! No matter how hard you try to steer, with the front end being light due to gravity pushing on the rear, you MUST modulate the throttle carefully. Remember, minimal tire spin. Soft tires (low pressure) helps here.

Third: when going downhill, be careful that the rear end does not swing around and meet you in front! I like using both front and rear when going down hill. It allows all tires to have traction, resisting the "breakaway" feeling. Engine braking is very important here and having all four tires helping makes a big difference. Sometimes when in open-diff rigs going downhill, the two tires (1 front, 1 rear) that are holding the rig back, hit loose soil or get air, allowing the rig to "lurch" forward--I call this the "lurch effect"--and it'll scare the heck out of you. Sometimes light pressure on the brake pedal will work, but I don't like using the brakes on the trail unless absolutely needed. Using engine compression with lockers is most advantageous 'cause all 4 tires are adding traction and resistance.

Fourth: steering is hard to do especially on hard surfaces like slick-rock, granite faces and boulder outcrops. When you are on a "bind" (no not binge!), the lockers will hinder your turn. You need to disengage the front end (ARB) and "bump" the throttle to allow slack in the gears to disengage the lockers. With mechanical, you need to play the throttle softly to allow the turn. Sometimes when I come out of an obstacle, the rear end will "steer" me straight even if the front is unlocked. So, if I can I will disengage (ARB) the rear as well. The Detroits will clank and bang, the Lock-Right will click and clack, but it's the best you can do. When I did have mechanical lockers, I would run the front end unlocked, the hubs free, in 4WD low using only the rear end and the mechanical locker in the rear. Then when I needed to "get to it," I would lock the hubs in! In mud and soft dirt/sand, the rear locker will steer you straight, even though you are turning the front tires! Again, throttle steer using some of the finesse at the foot. Let the tires slow down, then blip the throttle to "pull" the front end around.

Note: Air lockers can be engaged anytime they're needed. Just don't be spinning the tires. Engage them moving or not; disengage them anytime, but you need a moment of slack to make sure they unlock. Having lockers means you need to pay more attention to the vehicle and its handling characteristics. Add big tires aired down to 12 psi and it takes some finesse to make turns and keep the vehicle aligned. Driven responsibly, lockers are a great help. They actually reduce environmental abuse due to all four tires helping, not just two spinning.

ฉBill Burke’s 4-Wheeling America LLC

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คำตอบที่ 6
       ขอบคุณ น้าtota มากครับ

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