The Basics of Lift Assist Hinges and Stays
This page will introduce you to the basics of lift assist hinges and stays: their mechanism,
different available types, and how to use them.
Try out our lift-assist hinge / stay selection tool when you are ready to choose.
What Does Lift-Assist Mean?
What Does Lift-Assist Mean?
Lift-assist refers to a function that allows heavy doors or lids to be opened gently and effortlessly.
Even large device covers can be opened easily with one hand, reducing physical strain. Lift-assist is also sometimes called power-assist.
There are two types of products that provide lift-assist functionality: hinges and stays.
They can be used on the covers of food machinery, soldering equipment, chip mounters and so on.
They are also ideal for large lids that open and close frequently, such as on large-scale analytical instruments.
Why Does it Open Gently? - The Structure of a Lift-Assist Hinge / Stay
Lift-assist hinges and stays utilise the counterforce of springs to lift heavy objects with ease.
As shown in the illustrations, you can achieve an ideal operational feeling by appropriately choosing between two types of spring structures for specific applications.
Compression Spring
Counterforce is generated when the compressed spring returns to its original state.
Torsion Spring
Counterforce is generated when the coiled spring attempts to return to its original state.
Types of Lift-Assist Products
Types of Lift-Assist Hinges
HG-PA
Our standard lift-assist hinge.
Its lift-assist function allows for heavy lids to be opened with ease, while the soft-close function ensures a slow and gentle closure.
It is compatible with various types of installation, including exterior mounting and rear mounting for installing on the outside of a lid, and interior mounting for installing on the inside of a lid, which provides devices with a neater-looking exterior. It can also be used on a wide range of lid shapes, including L-shaped or box-shaped lids.
Lift-Assist Torque Hinge
This hinge combines a torque hinge—capable of holding a lid firmly at any angle—with a lift-assist function.
The lift-assist feature makes lid operation easier than with conventional torque hinges.
Stainless Steel Lift-Assist Hinge HG-JH210
A lift-assist hinge made from stainless steel.
The soft-close feature allows for slow and gentle closing.
Types of Lift-Assist Hinges
S-AT
Side panel mounted
Back panel mounted
Our standard lift-assist stay.
Its lift-assist function allows even heavy lids to be opened effortlessly. Certain products in this range can be combined with an optional damper unit for slow and gentle closure.
Two mounting options are available: side panel mounting, where the stay is fixed to the inside side panel of the enclosure, and back panel mounting, where it attaches to the inside rear panel.
The product is compatible with a variety of lid shapes, such as L-shaped and box-style lids, and offers an extensive line up.
Some models also include a lock hole to prevent the lid from accidentally closing during operation.
S-ATH
Heavy-duty lift-assist stay.
Its lift-assist function allows even heavy lids to be opened effortlessly. The torque can be fine-tuned by turning the adjustment bolt.
Click here for product examples
Please note: Some damper stays also offer a lift-assist function, enabling doors and lids to be lifted with minimal effort.
Benefits of Using Lift-Assist Hinges and Stays
Gas springs can also open heavy doors and lids with minimal effort, but their structure differs greatly from lift-assist hinges and stays.
Gas springs do not actually use springs to expand and contract, instead relying on gas and oil pressure.
Gas springs are compact, yet capable of exerting great force. However, they do have the disadvantage that the gas leaks out over time.
On the other hand, lift-assist hinges and stays utilise spring counterforce, so there is no need to worry about gas leakage and they can be used with confidence over extended periods.
Selecting Lift-Assist Products
Lift-assist products apply force (torque) generated by spring counterforce to lift lids and covers.
When selecting a product, it's important to ensure that the torque of the lift-assist product is appropriately balanced with the lid's moment.
What Is Lid Moment?
The moment of a lid refers to a force that causes an object to rotate around a certain point.
The moment varies depending on the angle the lid is opened to, as shown in the diagram. The amount of force required to rotate a lid increases the nearer the lid gets to being horizontal to the ground, and decreases the closer it gets to being vertical.
- Open at 60°: smaller amount of force required to rotate the lid
- Open at 15°: larger amount of force required to rotate the lid
To open lids easily, we recommend that the product's torque value (the force required to lift the lid) be greater than the lid moment (the force required to rotate the lid).
If the lift-assist product's torque value (the force required to lift the lid) is greater than the force required to rotate the lid, the lid can be opened with minimal effort.
On the other hand, if the force required to lift the lid is too great even when the opening angle is 0°, the lid will not close completely, so when the opening angle is around 0°, the lid moment (the force required to rotate the lid) needs to be greater than the product's torque value (the force required to lift the lid).
When the force required to rotate the lid is greater than the lift-assist product's torque value (the force required to lift the lid), the lid will close securely.
The formula for calculating the lid moment is as follows.
from centre of rotation to centre of gravity
Solve complex moment calculations with our selection tool!
Also simulates operating force!
Use our MDT Selection Tool to choose products that suit your needs,
just by entering the distance to the centre of gravity and the mass of the lid.
