e. 73 non-limited slip 3L — 3. Differentials- Open vs Limited Slip: Generally, your Ford Ranger came with either an open differential (power is only applied to only one wheel), or a limited slip (the power is applied to the wheel with the most traction). If you have a vehicle, then one thing that you might not have given some thought to has […] Nov 26, 2019 · Open differential (standard) means both rear tires must have traction to move the vehicle forward. Selectable lockers may provide more benefits than automatic diff locks, but either one is going to improve off-roading performance and capabilities when it comes to tackling tough obstacles on the trail. Obviously 4x4 or 2WD is a choice on its own, and I'll need to make that decision. To diagnose the P1832 Ford code, it typically requires 1. where can i get a locker? what are lockers? 2010 F150 rear diff locker? powertrax lock right locker; What's not to like about Powertrax No-Slip? powertrax vs LSD; Keywords: locker locking diff differential axle rearend powertrax lsd limited slip posi grip slip traction rwd 4wd tractionlok Jun 29, 2021 · Where the 2021 Ford Bronco differs from the other vehicles that offer a front locking differential, is that the Bronco does not need to have the rear differential lock engaged to utilize the front To activate the system, pressing an axle lock switch once locks the rear axle, while a second press locks the front axle. Jul 3, 2018 · 2015 - 2020 Ford F150 - 2018 F-150 4x4 differentials - I called several dealership service departments and got a range of answers to this question, before it occurred to me that the people in service departments who answer phones often know little about cars - they are there to book an appointment for you. 2007 Ford Super Duty Axle Codes: 37 — 3. The lack of differential between axles and different rates of turn when cornering will destroy the transfer case if you drive on dry pavement. If either of these do not work, your 4X4 won't work. (See my signature for what my new F150 came with. If I understand correctly, LS is Sep 6, 2011 · SAme when you swith off, it stays locked untill you get differential action, then will it disengage Diff lock can be used on any terrain where wheel slip is present, i. While all of these systems offer their pros, they also have their cons. Whether fitted to front, rear or both differentials, Traction Performance is significantly improved in all realms of 4×4 and 2×4 performance activity. The E-locker on 2011's To further increase capability, the system includes the Rear Differential Lock feature. Take for example the Ford Maverick / Bronco Sport optional AWD system. Jul 25, 2022 · A 4x4 Carry truck equipped with axle lock, and diff lock can be a perfect work machine with the ability to traverse a wide range of terrains. Apr 27, 2023 · 2021+ Ford F150 - Accidentally Driving w/ 2H rear diff lock on - Hi all! Purchased my 3rd f150 last week. When you lock a differential, the axle can turn both wheels simultaneously regardless of any traction difference. The Auto salvage yard down the street just got in a f-150 (same model not sure of the year) that is a super crew 2wd, but I looked inside and it has the Electronic locking rear Jun 2, 2022 · I'm assuming the 31 correlates to a 3. The purpose of a locking differential The ever-faithful Dana 60 axle setup does a pretty good job of taking care of your truck off-road, but it can't get you out of everything. Here are a few reasons why you may consider investing in a locking differential. * Always consult the owner's manual before off-road driving, know your terrain and trail difficulty and use Feb 10, 2010 · The 4X4 works with two systems - the shifter on the floor manually engages the transfer case. This is the solenoid that engages/disengages the transfer case when you rotate the 4wd switch on the dash. 73 ratio and e-lock Feb 2, 2012 · Basically a part time spooled diff. A rear differential lock is designed to split torque on the rear axle so 50 per cent is directed to each wheel. 31 to 3. Known also as diff-lock or locker, it is a modification to the standard differential. co. “Vehicles with a centre diff (and no lockers) can deliver drive to any of the four wheels of the vehicle, but the power will still only be delivered to one wheel and May 3, 2022 · Locking differentials, or “lockers”, allow you to lock the center, front, or rear differential to evenly distribute power and torque to all the wheels on the vehicle. But since it’s a relatively new feature, it’s not the most reliable. In this differential there are friction clutch discs that lightly 'lock' both axle shafts together when driving straight as long as both tires have equal traction. I know about it's locking differential in 4x4 hi & low but is it possible that it has a limited-slip differential while in 4x2? or do we only have a single drive wheel in the rear? Air Locker Differential Ford 10", 40 SPL RD249CE $2,465. : Articles The bad thing is that it only works at speeds under 30 mph, and when not engaged the rear end is an open differential. 00. If you are somehow getting a true 4x4 be careful as you will tear up u-joints,splines or worse yet spiders in the axle itself. Jan 6, 2009 · I have a 580k also. A center diff lock is a mechanism that shares power equally between the front and rear axle of a vehicle. 73 but doesn't have the electronic locking; 9. Sep 4, 2014 · Another difference is how the lock-up action occurs. A complete and thorough explanation on how four wheel drive (4WD) 4x4 systems work. May 23, 2023 · The differential locks when a PWM controlled magnetic field coil located inside the differential energizes. The differential allows this to happen. It did NOT come with the electronic differential lock (may be called something different) Just the switch for H or L 4 wheel drive. My Amazon "Top Picks" - https://www. 0 the rear diff lock also engages. Jan 16, 2024 · General F150 Discussion - rear differential lock stuck on - I noticed the rear end grabbing when I turned in my 2014 f 150. The only "mod" is to remove a tang off the speedometer tone ring before bolting it onto the carrier. The way the limited slip axles work is there is a clutch pack inside the diff. 5). That little wire is a feedback, when the diff engages it lights up your display. Installation means replacing the factory diff case with this unit and setting up preload and tooth contact pattern. The diff lock button only switches the light on and off. This system While shopping, you’ll likely hear the term Limited Slip the most. Remember, the diff will not engage while it stands stillthe old 2. No Difflock with EBD / Traction Control on. I have been following a diagnostic procedure from the 2011-2016 model trucks, trying to pinpoint what is causing my "check locking differential" message on the dash when I pull out on my 4x4 ****. • The electronic locking differential will not engage if your vehicle speed is above or 56 mph (90 km/h) in 4X4 Low. The Ford Ranger Wildtrak 4x4, Sport 4x4, and XL 4x4 have Electronic Locking Rear Differential. You can engage this mode when one wheel is on the ground and the other is spinning in the air. What is the price of the Ford Ranger in the Philippines? Wondering what kind of off-road tech is on the new Ford Ranger? Wonder no more! Paul Maric tests out every single 4WD feature in the new Ford Ranger to see i Feb 20, 2024 · I find it a bit surprising because I own several class 8 trucks with lockers and with those trucks I often find it necessary to lock the axles to gain traction in snow. make sure the diff lock is engaged before flooring it, otherwise if wheels spin at high speed and the DL then engages you will break something The electronic locking differential is a device housed in the rear axle that allows both rear wheels to turn at the same speed. 0. Sep 4, 2012 · There is a solenoid on the passenger side of the transfer case. sand, loose gravel, mud, etc. How critical Oct 30, 2015 · 2009 - 2014 Ford F150 - 2012 F-150 Electronic Locking Rear Diff - Traded for a 2012 F-150 with the offroad package a couple months ago. This differential will direct power to the wheel that is easiest to rotate – providing different power to each wheel according to its needs. The only time you'd want one is if you're rock crawling and using up a lot of axle articulation on a regular basis. A spool functionally locks both wheels together so that they must always turn at the same Feb 5, 2019 · My demo will show you what Locking Rear Differential button does and how to use it. The Twin-Clutch rear drive unit that can shuffle 100% of torque to either wheel and simulate a locking differential More than traction control, new AWD systems are getting very good at optimizing traction. If the actuator's housing is cracked or damaged, debris can build up and cause the wheel bearings to wear as well as cause lubricant leaks, which can eventually lead to a damaged 4WD system. Like I said, with my pick up, if the truck doesn’t move in 2 wd locking the rear axle never makes the difference. Front tires are rolling along (since connected to the axle, they make the front drive line parts rotate) - only rear tires are pulling. Losing the extra flab of a 4x4 transmission and extra diff and axles generally results in a reduction of around 100-150 kg in the kerb weights of high-riding 4x2 utes compared to their 4x4 siblings. it is a 1988 4wd and the diff lock only locks the rear wheels even when you have the front axle engaged. try locking in the 4wd and raise the front off the ground with the bucket,then creep it forward in 1st gear and see if both wheels turn together. In 2wd, they will still spin free but the hub will already be engaged when you throw the switch. Other than unplugging it at the diff, Jun 24, 2017 · The following conditions will affect the electronic locking differential: • The electronic locking differential will not engage if your vehicle speed is above 20 mph (32 km/h) in 4x2 or 4x4 High modes. Oct 29, 2010 · 2011 ford super duty electronic rear differential lock . A Limited-Slip Differential works much the same as an open diff; it is intended to keep the wheels moving equally at different vehicle speeds. 28 spline pinion I'm not sure, but a True Trac torque biasing, gear driven limited slip fits the Dana 60 front diff with 35 spline axles. Instead of being either locked or unlocked, but not in between, a clutch-type LSD can put pressure on the clutches to increase the break-away torque required and allow slip when that happens. Depending on the ute, a rear differential lock can be used in two- and four-wheel drive modes and generally only up to a certain speed. I am not sure what the 3E is, but I'm assuming it is the newer 10. Sep 1, 2009 · A spool, which replaces the differential, is sometimes mentioned as an option to a locking differential. Rear Differential Lock takes advantage of the twin-clutch hardware to allow greater off-road performance, similar to a traditional mechanical locker. Instead, they come with an “automatic-locking” internally named the G80. ARB offers one of the world’s most famous and proven locking differentials, the ARB Air Locker. Apr 13, 2015 · 8. If you have an axle diff lock, both wheels on the axle will drive but turning will become more difficult. 75" HD: The heavy-duty diff for, presumably, the HD Payload Package vehicles and only comes with 3. Jan 21, 2017 · • The electronic locking differential will not engage if you press your accelerator pedal beyond 50% during an engagement attempt • In 4x2, 4x4 Auto, and 4x4 High modes, the electronic locking differential will automatically disengage at speeds above 25 mph (41 km/h) and will automatically reengage at speeds below 20 mph (32 km/h) Mar 9, 2020 · This is the front axle (open) in my 2020 F-350 - XLT 7. 2017 F250 Build Date 10/2017 with the FX4 package and Electronic Locking Diff. 9. 30 non-limited slip And then when you look down at the transmission lever, there is another cluster of buttons that adjusts for the 4X4 modes, allows activation of the rear diff lock, choice of Low Range (Yes, the Everest is a proper 4X4 with low Range), hill descent control, auto-off, and even parking sensors. 8": The standard diff that runs the gamut of ratios from 3. Nov 16, 2011 · At first I thought that 4x4 switch was open diffs and the hub locks were to lock the diff (the front one only of course. There are a few different types, but before we get into why you’d want to lock your differential, we need to explain what a differential is. ) I used to have a 1990 Ford Van that had a 4x4 Jan 11, 2020 · Quick video showing how to manually lock the vacuum actuated hubs on Ford Superduty as well as a brief explanation on different 4x4 systems. The clutch-type LSD can also provide a lock-up during deceleration. Feb 22, 2017 · 2015 - 2020 Ford F150 - Advice for using E Locking Differential - My experience using a 4x4 is relatively limited and I don't understand when it would be beneficial to use the electronic locking differential (ELD). What would be the situations where I would want the Traction Control button to be OFF? I'm assuming this would be some type of bad situation off-road?? 2. It’s supposed to make off-roading easier by managing wheel spin. One of the most interesting and innovative changes is an electronic locking rear differential, comparable to the GKN-made e-locker included with the F-150… read more Dec 8, 2011 · That worked quite well. The ARB Air Locker is a replacement differential carrier that can either function as a conventional differential or lock both front and rear axle shafts together. Jeep Rubicon has a similar device from the factory. A differential lock is designed to ensure one wheel can’t Jan 5, 2023 · I put a SPE Full Lock Diff Kit on my 2014 F150 4x4 and it worked great. Nov 11, 2021 · How To lock a rear differential on a 2019 Ford F150 XLT. 0 hour of labor. Jan 16, 2022 · Most of these vehicles offer an electronically locking differential. I discovered that if I pushed up on the knob the light would go off and the lock was disengaged. I know about it's locking differential in 4x4 hi & low but is it possible that it has a limited-slip differential while in 4x2? or do we only have a single drive wheel in the rear? Jul 31, 2011 · 2009 - 2014 F150 - Limited Slip vs. Jan 30, 2020 · What is the Cost to Diagnose the Code? Labor: 1. Driving 4L (4X4 LOW) - Uses extra gearing to provide maximum power to all four wheels at reduced speeds. Locking differential discussions in the F150 forum. This mode is not intended for use on dry pavement. The indicators will be lit. What is diff lock on 4X4 vehicles? Have you seen these on Toyota or 4X4 vehicles? A locking differential (or diff locker) can make a significant difference in the performance of your 4wd in certain situations. The workshop manual has much more extensive discussion than just the above about the operation of the ELD system, including control logic flow diagrams and Dec 8, 2016 · 2015 - 2020 Ford F150 - 2016 F150 Differential Lock Question - Hi I have a 2016 F150 4x4. For general, on road 4wd use, I keep the hubs in the auto position. . Cars only have one differential, but 4X4 vehicles can have up to three differentials – front, centre and rear. Jun 23, 2020 · That’s why Ford installed a diff lock in its high-riding Falcon RTV 4x2 ute in the mid-2000s and why Ford also provides one in today’s Ranger Hi-Rider 4x2 ute. Back in the early 80's I was prepping new cars for a dodge dealer, my favorite one was a omni that came in with Horizon wheels and stickers on one side and omni wheels and stickers on the other. What else do you Dec 3, 2018 · In this video we illustrate how to identify the different Ford Differentials and which ones require friction modifier to be added to new fluid when servicing Aug 17, 2022 · The term diff-lock is an abbreviation for a lockable differential, and they’re also known as lockers. I would have to push it in to engage and the dash screen 4x4 icon did not show when engaged. 5 in my 2001 rear. LOKKA is an automatic differential locker that is invaluable for Off-Roading. amazon. Electronic Locking Differential - I'm trying to decide among 4x4, LS, or ELD. New truck is a 2021 Roush XLT edition. The axle locks will disengage if the vehicle is taken out of 4L (Low) range, or the ignition switch is turned off. The OP was asking if the FX4 was worth it over an XLT 4x4 with the optional locker. He was also looking at another model without the locker. these things happen. When in true 4WD a vehicle should only be driven on surfaces that can slip (dirt/gravel/mud). I am currently running a Ford E-locker from a newer 2011+ Super duty 10. In their latest venture, Ford has struck their version of the best of all worlds as they see it with the introduction of the Integrated Wheel End (IWE) actuator system. Putting it into 4 wheel drive always makes the difference. 73, but with e-lock. If I were plowing or off road driving, I'd lock the hubs before starting to keep them locked in. Compare all Ranger models' specs and features here . My question is as follows, I accept any jokes coming my way in advance but this truck has a million more buttons than the past 2. Nov 14, 2014 · 2009 - 2014 Ford F150 - Locking diff stuck "ON" - I have a 2012 Screw, my 4x4/ELD switch is apparently broken, and the ELD is stuck turned on. How to use diff lock properly. “Vehicles with a centre diff (and no lockers) can deliver drive to any of the four wheels of the vehicle, but the power will still only be delivered to one wheel and Feb 15, 2022 · Hoping someone can help me out with this one. In 4WD with hubs disengaged front drive shaft, front diff and front axle, rear drive shaft, rear diff and rear axle are rotating. Benefits of locking differentials Nov 1, 2020 · Rear differential lock explained. Find out more at www. With a limited slip differential, a clutch pack internal to the differential allows some torque to go to the non spinning tire to help you get out. Jan 13, 2016 · 2015 - 2020 Ford F150 - Traction Control & Diff Locker Questions - 1. While your four-wheel-drive is designed to receive power (drive) to all four wheels, power can only be delivered to a maximum of two wheels at any one time without the assistance of a differential lock. 73 limited slip 41 — 4. Ford Ranger XLT 2020 SiT 4x4 (South African Version: Single Turbo - 134KW - 420 NM - 10 Speed Au Apr 21, 2024 · The Electronic Locking Differential (ELD) is an advanced differential system used in F150s and Ford F-Series Super Duty trucks. Oct 1, 2009 · The 2011 Ford Super Duty trucks will ride down the road with a lot of new ideas in the future that will make them faster and more efficient in many different situations. If you frequently take your Super Duty through uncertain terrain but enjoy the smooth turns and efficient torque transfer of an open diff, the Eaton E-Locker Electronic Locking Front Differential is for you. I found that if you grab the very This is where undue torsion is created on the tyres or axle, aside from this torsion, one wheel may get dragged when cornering if diff lock is left on. Apr 2, 2012 · Ye you won't have power to the diff. I noticed that the rear diff lock light was on on the dash. Feb 8, 2024 · Locking differentials are a type of differential used in vehicles to improve traction and handling, especially in off-road or challenging terrain conditions. The electronic locking differential provides additional traction should your vehicle become stuck. I could engage and disengage anytime or speed. There are two types of diff lock: automatic and manual. Jul 16, 2022 · During a turn, the inside tire of your axle is moving more slowly than the outside tire. Oct 20, 2022 · A centre diff lock is essential to ensure drive to both the front and rear axles; although, diff locks front and rear are still required to spread drive evenly from side to side. 10 non-limited slip 43 — 4. Oct 22, 2023 · Whenever I engage 4wd on my 2021 Wildtrack 2. The driver can lock the differential by pressing a button in the cab. That's about 5-8 bags of builder's cement, which is a lot of performance-sapping bulk to be lugging around if you don't need it. Furthermore, you control the locking function as a driver. It also causes a relay to ground one of two solenoids that cause vacuum lines to activate an actuator which engages the front differential. You can activate the differential electronically and shift it on the fly within the operating speed range. I pulled fuse #34, which should be the 4x4 switch, and the ELD is still on. Locking Differential Cons Jul 26, 2019 · Selecting the best limited-slip or locking differential for your 4x4 depends on many factors, including the type of off-roading you do, how much time you spend off-road, your driving style and Apr 6, 2018 · 2009 - 2014 Ford F150 - Electronic Locking Rear Differential Swap - Hey guys I have a 2014 Super crew F150 XL 4x4 with a 3. 5 sterling (2011+). Let's have a look at what makes the Carry so popular as a compact and capable off-roader by digging into its 4x4 drivetrain. The HD Tow package also has a 4L button, in addition to the 2H and 4A buttons that all 4x4 Expeditions have. Feb 27, 2020 · When’s the best time to engage low gear, and when should you lock the diff? See them in action. I unplugged the switch from behind, and it's still stuck on. this is why mechanical lockers will "clunk" during a turn in a parking lot. I purchased it a couple of weeks ago and found this issue when reversing up a gravel drive. This enables maximum drive torque to be transmitted to both truck wheels. Rear lock differential is a system that splits torque 50/50 between the rear wheels. However, I just want to make sure I understand the difference between LS and ELD. ford. Feb 18, 2022 · Diff lock is a locking mechanism that locks both wheels on an axle together, rotating at the same speed. When the locker is engaged, the tires are forced to move at the same speed which means that one side of the axle is going to be forced to slip. With no give, locked diffs can snap axle shafts, stubs, and/or CVs quite easily if there is a sudden, drastic increase in traction for a tire Jun 18, 2015 · The 4WD axle actuator is located underneath the front end of your truck, and is naturally exposed to dirt, debris, salt, or other road threats. With some vehicles, such as the Mitsubishi Triton, only the top-spec Exceed variant is equipped with a factory rear diff lock, while a rear diff lock is standard across the Ford Ranger 4x4 line-up. In contrast, the limited slip in my 2010 ford was worthless. Diff lock allows a vehicle to gain traction in extremely difficult conditions, such as one wheel slipping continuously on a wet surface or a slippery rock face. If one tire is on ice or snow or in mud, all power will go to that tire and it will spin uselessly. for us old hot-rodders. When engaged, RLD ensures that the two wheels rotate at the same speed. It does this by regulating the power from the engine and dividing it between the two axles. The specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. A Nov 13, 2016 · The abs wheel sensor use to be top center of the differential housing, now I believe they have one at each rear wheel, what you have in your hand is definitely the e locker connector, you now no longer have use of it until you repair that. Dec 29, 2021 · It does come with the locking diff. 75": The step up diff, again running the range from 3. . Nov 8, 2023 · You can use rear lock differential mode with either 2WD or 4WD modes. 2002 (2wd) and 2013 fx4 prior. 55 LS differential. There are a variety of differentials available for the Ford Ranger, depending on what axle you’re working with. In 2wd I can switch rear diff lock on and off as normal. Most manual diff locks are activated by using a switch on the dashboard or gearstick and they function using compressed air, an electromagnet, or are cable-operated. Front tires are rolling along (the transfer case makes the front drive line Dec 29, 2019 · A centre diff lock is essential to ensure drive to both the front and rear axles; although, diff locks front and rear are still required to spread drive evenly from side to side. Fine on the street as your diff acts like an open center unit until you engage the locker with the flip of a switch. I noticed my Aug 8, 2023 · Locking Differential Pros. com/shop/toyotajeffinraleigh⬇️ Jan 11, 2019 · It more likely the wrong center console was installed. The switch powers the solenoid which when opens allows the vaccum from the engine to engages the diff. My truck did not come with a rear differential lock (didn't get the FX4 package). This locks the differential side gears and creates the locked differential. SPE hasn't made a kit for the 2021 F250 or else I would have it again. nz/commercial/ranger/leading-ideas/. Driving on Hilly or Sloping Terrain Although natural obstacles may make it necessary to travel diagonally up or down a hill or steep incline, you should try to drive straight up or straight down. The clutch offers resistance to the axle shafts turning against each other, like a brake on a wheel - it doesn't lock the axle up it just resists it moving. Dec 12, 2009 · 2009 - 2014 F150 - FX4 Locking Differential - I bought a 2010 FX4 S-Crew on Monday and love the truck. Diff Lock On vs. 3L gas Ford Dana 60 (unlike the Dana 60 of yore) with Ford logo on the cover 35 spline axle shafts short reverse open diff ring gear diameter: 10 in. 73 LSD axle (SRW, Sterling 10. Regardless of which diff lock you choose, the doubling of grip they can deliver will make your 4x2 or 4x4 ute a more effective workhorse. ) That would make sense right? But, when I flip into 4x4 the front wheels don't actually spin unless I also lock the hubs. Air Locker Differential LR Discovery 3, RR, 31 SPL RD218 $1,091. The light for the diff lock does not come on. Do you really need a rear locker? No. Electronic Diff. Supplied by DANA, it’s an on-demand AWD system. These are exactly what they sound like, with automatic diff locks kicking in as soon as it detects that a Jan 12, 2024 · Perhaps worst is the increased likelihood of breakage. May 3, 2022 · A quick description of what rear differential does, why it can sometimes work against you, and how to lock the rear differential so the tires spin at the sam If the front or rear axle is submerged in water, the axle lubricant and power transfer unit lubricant should be checked and changed if necessary. May 3, 2021 · Ford has utilized everything from manual actuated wheel-end locks to fully automatic hub assemblies. Only problem was that it worked in reverse with the dash ****. Jan 4, 2022 · I lock mine from time to time in 2wd to ensure things are operating freely. Sep 29, 2017 · Having a rear differential lock, like the one in the Ford Everest 4WD, can be handy if you’re on a section of sand that’s very bumpy and is likely to cause your 4WD’s wheels to lift off the Jan 12, 2013 · 4H (4X4 HIGH) - Used for extra traction such as in snow or icy roads or in off road situations. 00 Air Locker Differential Toyota Tacoma May 29, 2019 · If you can’t locate a rear diff lock switch, have a look in your vehicle’s owner’s manual. The indicators will flash prior to being fully locked or unlocked. The General Motors vehicles on this list do not have an electronically locking differential the driver can control. May 29, 2019 · If you can’t locate a rear diff lock switch, have a look in your vehicle’s owner’s manual. Jul 3, 2023 · This is actuated with a button next to the Driving Mode control, looks like a picture of the axles with a lock on the rear axle. 5 I had to sway left and right, common technique to engage the diff, both on my 4x2 and 4x4 Jul 14, 2016 · As such, all powered axles – front and rear in a 4WD - have a differential. Mar 12, 2004 · An alternative to a locking differential, and one that is offered as an option on most trucks from the factory, is a 'limited slip' or 'posi' differential. This video will look into depth on how part time and full time four wheel Jan 12, 2005 · 1999 to 2016 Super Duty - Superduty auto-locking 4X4 hubs - Can someone explain to me how the auto-locking hubs on a Superduty work, in-particular the auto part? I recently had trouble with mine and replaced them with a set of aftermarket manual hubs that the manufacturer insisted were the correct application. Nov 11, 2020 · Manual diff locks are controlled by the driver and they can therefore decide if and when extra traction is required. hf zc cz up tx ds ir ib rw wm