Historically, to elevate materials, companies either invested in a costly freight elevator or relied on staff to manually lift and move materials or goods. Then, about 25 or so years ago, another option came to market – vertical material lifts. These lifts, also known as material lifts or VRC (Vertical Reciprocating Conveyor) lifts, became the perfect in-between solution. There are two main types of vertical material lifts: the hydraulic lift and the mechanical lift.
For one, VRC lifts are much less expensive than freight elevators. What’s more, they provide a safer working environment, increase productivity, and save wear and tear on a worker’s body by reducing the manual labor needed to move materials.
In addition to less manual labor, and improved safety and productivity, material lifts offer a host of other benefits. To read about them in more detail, click here to read our article titled: Top 10 Benefits of a Vertical Material Lift.
Each has its advantages and disadvantages. In this week’s article, we’re going to provide a side-by-side comparison of the two different types of vertical material lifts: hydraulic lift and mechanical lift.
Two Types of Lifts: Hydraulic and Mechanical
What are hydraulic material lifts?
Hydraulic lifts and hydraulic elevators work similarly to those found in cars and heavy equipment. The hydraulic system is based on Pascal’s principle of transmission of fluid-pressure that demonstrates how compression fluid generates power and control.
How hydraulic freight lifts work
Hydraulic elevators are powered by a piston set inside a cylinder. An electric motor pumps hydraulic fluid into the cylinder, which moves the piston, and the piston moves the elevator cab upwards. As the hydraulic fluid is released, the elevator cab descends.
What are mechanical lifts?
Mechanical lifts are the second type of vertical lift. Different than a hydraulic lift, mechanical lifts operate with a cable or chain lifting system. In a VRC lift, the platform is raised and lowered by steel cables or chains.
How mechanical lifts work
In a roped elevator, steel cable ropes are attached to the elevator cab and looped around a sheave or drum. The sheave or pulley grips the hoist ropes, and as the sheave moves, so do the hoist ropes via an electric motor. When the motor turns one way, the sheave rotates and raises the elevator; when the motor turns the other way, the sheave lowers the elevator
The lifting process is similar to a VRC lift. Here, steel cables (or chains) are attached to a platform. But instead of a sheave, VRC Lift cables loop around a drum (chains loop around a gear). The drum or gear rotates via an electric motor to raise and lower the platform.
Why are mechanical (motorized) VRCs better than hydraulic VRCs?
Both hydraulic lifts and mechanical lifts elevate materials and/or goods from one level to another, yet they differ vastly in terms of how they’re made and maintained. Let’s take a look at the chart below.
|Vertical Material Lift System Comparison|
|Fluids||Will never leak.||Will eventually leak. Slight seepage is considered normal. This is an environmental issue, as hydraulic fluid is extremely toxic.|
|Lifting Force||Driven by an electric brake motor cyclo-reducer, which lifts the platforms with cables or chains.||Electric motor drives the hydraulic pump forcing fluid thru a system of control valves, flexible hoses, and cylinders. Higher applications must also add cables or chains, increasing complexity and maintenance.|
|Cycle Limits||100% duty cycle.
(Lift usage is not limited)
|Only 6 cycles per hour average.|
|Travel||Steady & smooth. Precise positioning with limit switches.||High oil temperature, which could lead to a lift shutdown, can cause jerky and inconsistent movement. Precise intermediate stops and leveling are not possible due to hydraulic drift.|
|Noise||Very quiet.||Higher noise level. High pitched whine.|
|Maintenance||The cable will stretch over time, but that is all that will have to be replaced.||As the unit ages, the hydraulic pump, cylinders, chain, seals, packings, and hydraulic oil will need to be replaced for the lift to continue to move the rated capacity.|
|Lifting Capacity||No difference||No difference|
As you can see, the mechanical VRC lift is a better choice in 6 out 7 categories. It is a better choice for quality, life expectancy, and maintenance. Lifting capacity was the one category where the advantage didn’t go to either lift type.
Mechanical lifts are quieter, able to run continuously, and because they don’t use hydraulic fluids and don’t leak like a hydraulic lift, much more environmentally friendly.
Mechanical lift vs. hydraulic lift cost of ownership
The one advantage of hydraulic lifts is their initial upfront cost; hydraulic lifts do cost less. However, the initial cost pales in comparison to the high maintenance costs incurred over the life span of the unit. By far, mechanical lifts are a better value and offer a better return on investment.
With the advent of the vertical material lift, warehouses and distribution centers have an alternative to an expensive freight elevator. We put this side-by-side comparison together to show the differences and similarities between the two types of lifts.
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