This article explains the difference between 4H and 4-Lo and their uses. Engaging 4-H and 4-Lo at the right time is of utmost importance for the longevity and protection of your transmission, transfer box, and other drive-train components. The right gear selection for the terrain is important and as a 4WD owner, you need to understand what the differences are and exactly which situation calls for what gear selection.
What is the difference between 4H and 4-Lo and when should you use it? 4-H propels all 4 wheels and should be engaged when the driving surface becomes slippery and the risk of losing traction on your wheels increases. 4-Lo utilizes low-range gear ratios in the transfer box for optimum traction and power usability.
4-Lo should only be used at low speed when navigating over challenging terrains such as:
- Rock crawling
- Steep slippery inclines
- Steep declines.
- Mud & Ruts
To find out more about the correct usage of 4-Hi and 4-Lo and the different functionality of each, keep reading…
Table of Contents
The Difference Between 4H And 4-Lo – What Does it Mean
The main difference between 4H and 4-Lo is that 4Lo represents low-range gear ratios and is usually identified by a 4-Lo symbol which means your vehicle is in 4WD mode and engaging the low-range gearset. This means all 4 wheels are being propelled forward at the axles via the transmission and transfer case.
The “lo” represented in 4-Lo indicates that the low-range mode has been engaged in the transfer box. Most traditional off-road 4WD vehicles have a 2H, 4H, and 4-Lo setting. Vehicles with 4-Lo are equipped with a transfer case that uses much lower gear ratios to utilize the available power and torque of the vehicle.
4-Lo mode is designed for driving the vehicle through difficult terrain without placing undue strain on the gearbox, clutch, transfer case, and engine. Difficult terrain could be classed as any of the following:
- Loose beach sand
- Thick mud
- Rock crawling
- High Sand Dunes
- Steep loose Inclines
- Long tricky declines
- Deep River crossings.
The other difference between 4H and 4-Lo is that 4-Lo uses shorter gear ratios, hereby keeping the revs high and always in the vehicle’s power band/range. This makes stalling more difficult in 4 Lo which is important when climbing up steep inclines and declines. Many people are under the impression that 4-Lo increases the vehicle’s torque, however, it does not increase it, but rather only utilizes the existing torque easier and quicker by keeping the vehicle in a higher rev range and in the highest torque band of the vehicle. This ensures the vehicle’s power/torque is readily available.
When To Use 4H And 4Lo
Low-range or 4-Lo is a very powerful function of a 4WD and allows you to accomplish feats no 2WD ever could. You engage low-range to get you through soft sand, over tall sand dunes, up steep hills, and down difficult mountain tracks. It will even get you through deep mud or snow, and it’ll help you drive over boulders and deep ruts with ease. Use it wisely and your 4WD will, not only take you to many amazing places but also bring you back home safely.
The lower gearing also improves your 4×4’s capabilities because it uses the vehicle’s engine braking, which helps to control your progress and speed going downhill. This allows for more controlled handling without placing all the stress on the brakes alone.
Every off-road situation needs to be carefully assessed before you take it on. A good rule of thumb is to judge the speed vs the difficulty required to succeed. Remember, “As slow as possible and as fast and necessary”, no more, no less.
Generally, if you cannot engage 4H, 2nd, or 3rd gear to cross an obstacle or if you feel the obstacle will place too much mechanical stress on your vehicle then you are better off engaging 4-Lo and taking it slow and steady.
Can You Drive In 4-Lo On The Highway?
No, low-range gears are only used for slow-going, so do not use them on pavements or highways. In fact, do not use the low range at speeds faster than 40 mph as a general rule. With that said, you will not even be able to reach the minimum speed to keep up with the slowest highway traffic. Also, every highway has a minimum legal speed too.
Driving in 4th or 5th gear in 4-Lo is like going 3 gears back on your transmission. For example, in Lo-range, 3rd gear is almost equivalent to 1st gear in 4-Hi. And 4th gear in 4-Lo will be like driving in 2nd gear in 4-Hi. So ask yourself, would I would drive in 2nd gear on any highway?
|Low Range (4-Lo)||Hi-Range (4H)|
|3rd Gear||1st Gear|
|4th Gear||2nd Gear|
|5th Gear||3rd Gear|
Apart from the above-mentioned, your risk of causing major damage to the transfer case, gearbox, drive-train, or engine is substantially increased. That is because most vehicles are designed to drive 4-Lo for short periods through difficult terrain or obstacles. Not for overly extended periods at high revs. Once you are off the 4×4 trail sand, snow, or rocks, switch your vehicle back to 2H before you reach the highway.
Watch – How Fast Can You Drive In 4WD 4H
How Fast Can You Drive In 4-Lo?
When you are driving below 15 mph and you are negotiating a difficult or tricky obstacle then 4-Lo is recommended. Remember, If the driving conditions are extremely slippery like on snow or ice or you are doing a steep uneven mountain track or driving through thick mud, beach sand, or river water, then these are perfect conditions to engage 4-Low. This is why it is very important to be able to know the difference between 4H and 4-Lo and when to use which gears. If the driving conditions allow you to drive faster without risking damage to your 4×4 and you can safely go over 15 mpg, you can then confidently switch back to driving in 4H without any risk.
Always ensure you stop first before engaging 4-Lo and slow down before reverting back to 4-Hi.
Should You Use 4-Lo or 4H in Sand?
The first thing you should do before venturing on sand is to engage 4H and decrease your tire pressure to 16 psi is usually the magic number without too much risk of de-beading the tire from the rim. However, that said, and can be a slightly trickier situation to negotiate because the driving conditions can vary vastly.
For example, if the sand is compact and wet then a 4H could easily be used to drive over it without causing undue strain to the transfer case and gearbox. The vehicle would basically glide over the surface without any difficulty. However, if the sand is thick and loose and the surface is uneven, select 4-Lo and approach with caution.
On the sand, you always want to travel as fast as necessary but as slow as possible. Keep the momentum going and do not allow your revs to drop too low. 4-Low in 2nd and 3rd gear is perfect for thick sand driving. 4H is best suited for climbing steep dunes.