In order to remove a tire and wheel for service, the vehicle must be lifted so that the wheel assembly can be removed from the hub. A variety of approaches are commonly used- stationary lifts, which raises the entire vehicle is used by most shops, others use a combination of floor jacks and jack stands. Key objectives are to prevent damage to the vehicle, and to prevent the vehicle from falling.
The three types of stationary lifts in common use are: Two-post above-ground, In-ground, and drive-over above-ground. The two-post above-ground lifts are most popular because of their ease of installation, maintenance, and use. They can be used for virtually all types of automotive repair jobs. The in-ground lifts utilize four symmetrical lifting arms attached to a hydraulic unit in the concrete floor. The downside to these lifts is that repairs require removal of concrete to access the hydraulics. The drive-over lifts have many of the benefits of the two-post lifts, but they have a more limited range of body styles and vehicle weights that can be lifted.
Two-post lifts come in styles with either symmetrical or asymmetrical lifting arms. The asymmetrical arm configuration provides more floor space and makes it easier to open vehicle doors when positioned between the posts. Before lifting a vehicle, lift towers must be positioned at the vehicle’s center of gravity, which for most rear-wheel, four-wheel, and all-wheel drive vehicles is under the driver’s seat. For most front-wheel drive vehicles, the center of gravity is located under the steering wheel.
Before attempting to elevate a vehicle on any sort of lift, the lift equipment should be inspected for damage, cracks, leaks, or signs of broken components or excessive wear. The lifting arms should be extended to insure that the stops are in place. Lifting pads should be in place, and if adjustable, they should be checked to ensure they are fully operational.
Each year a number of injuries and deaths occur related to lifting vehicles, so it is imperative that users follow safety requirements and standards published by the Automotive Lift Institute.
In part two, we will discuss: maximum lifting capacity, using the ALI Lift Point Guide, and when to use floor jacks, and jack stands. We will also discuss importance of periodic lift inspections.
Reference: Tire Industry Association, Instructor Workbook, Module 4. 2011
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