How Do Pulse Vacuum Hubs Work?

by | Last updated on January 24, 2024

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Ford’s IWE system works off of engine vacuum. … For this design, the vacuum is placed on the system unlocking the hubs while the truck runs in 2-wheel drive mode. When shifting to 4-wheel drive, vacuum is released, which locks the hubs. This leaves the front axle locked for fail-safe operation.

How do vacuum hubs work?

Ford’s IWE system works off of engine vacuum. … For this design, the vacuum is placed on the system unlocking the hubs while the truck runs in 2-wheel drive mode. When shifting to 4-wheel drive, vacuum is released, which locks the hubs. This leaves the front axle locked for fail-safe operation.

How does vacuum 4×4 work?

The vacuum motor, which is mounted on the right side of the differential, moves an

axle clutch gear

that engages the right-side axle to the differential. The motor diaphragm uses two vacuum hoses—one to pull and the other to push—each controlled by a separate solenoid that’s commanded by the GEM.

Does 4WD work without locking the hubs?

The 4×4 Hubs on a vehicle is the device which engages the axle to the differential.

Without the hubs there would be no drive sent to the wheels

. … To be in 4 wheel drive they need to be locked and the 4×4 selected, this will transfer 25% drive to each of the 4 wheels.

How do I know if my locking hubs are bad?

  1. Not Properly Engaging. If you have a broken hub, your four-wheel drive will not be able to engage properly. …
  2. Noises. You may hear a grinding or slipping noise when the hub fails to properly engage. …
  3. Not Disengaging. On rare occasions, a vehicle’s automatic locking hubs may fail to disengage.

Is it bad to drive with your hubs locked?


It does no harm to run around with the hubs locked and front drive disengaged for the short term

. Over the longrun, though, you’ll average worse gas mileage, and have increased wear and tear on the drive train components and tires.

Is it bad to keep your hubs locked?


Leaving your hubs locked will cause no damage to your vehicle and will not influence it’s handling

. … By the way, locking hubs do not create more traction. They are not to be confused with differential locks! In 2WD with locking hubs disengaged rear drive shaft, rear differential and rear axle are rotating.

How do you diagnose a 4×4 problem?

  1. decreased traction in snow or mud.
  2. rattling noise when 4WD engaged.
  3. “Service 4WD” indicator light is on.
  4. can’t disengage 4WD (4WD light on).
  5. excessive front tire wear (4WD won’t disengage)
  6. excessive fuel consumption (4WD won’t disengage)
  7. lack of power (4WD won’t disengage)

How do you diagnose a bad 4×4 actuator?

  1. Difficulty engaging four-wheel drive. One of the first symptoms of a potential problem with the front axle engagement switch is difficulty engaging the vehicle’s four-wheel drive system. …
  2. Four-wheel drive becomes stuck. …
  3. Four-wheel drive mode does not activate.

How do I know if my 4×4 is engaged?

If the 4-wheel drive is engaged,

the driver will feel the left and right wheels bind up while driving

. The bucking or lurching motion of the car is normal and indicates the front end is under power. The vehicle will become a little bit stiffer when turning.

What is the point of manual locking hubs?

What are Manual Locking Hubs? Manual hubs are a type of

part used to disconnect a wheel from an axle in a four-wheel drive system

. This allows the wheels to rotate without having the front driveline turn. This saves wear and tear on the vehicle and also helps improve fuel economy.

Should my hubs be locked or free?

normally its a full time transfer case. Its actually best to lock the hubs in every 250 miles or so for a few miles. The rule of thumb is to leave hubs unlocked in

the summer time and locked in the winter time

. Having the hubs locks will cost in fuel economy.

What happens if you only lock one hub?

If you are in 4wd with one hub locked and one open the power would

follow the path of least resistance and spin the unlocked axle

unless you have a locked/spooled diff. In that case both axles would get power and only the wheel with locked hub would turn.

When should you replace locking hubs?

When this occurs, your vehicle will be difficult to steer at lower speeds. Again, if you suspect you have a problem with your locking hub, have it inspected and replaced if necessary. Technicians recommend that you have your locking hubs serviced and inspected

every two years

or 25,000 to 30,000 miles.

What does it mean to lock your hubs?

Locking hubs, also known as

free wheeling hubs

are fitted to some (mainly older) four-wheel drive vehicles, allowing the front wheels to rotate freely when disconnected (unlocked) from the front axle. … Unlocking the hubs disconnects the wheels from the axle, which eliminates this extra load.

How do you check manual locking hubs?

Lock both hubs, get under the truck, & turn the front d’shaft while

watching

the U-joints in each steering knuckle. The one that continues to spin is broken. If they both lock & you can’t turn the d’shaft any more, the t-case is the problem.

David Evans
Author
David Evans
David is a seasoned automotive enthusiast. He is a graduate of Mechanical Engineering and has a passion for all things related to cars and vehicles. With his extensive knowledge of cars and other vehicles, David is an authority in the industry.