LM Stroke, Bushing (Straight / With Seal) ST-UU Type, ST-UUB Type

Drawing

ST: UU type
(for light load)

ST: UUB type
(for medium load)

Specifications Table

Product Feature Details

Structure of LM Stroke ST Type

As shown in Figure 1, the ST type incorporates a ball cage and balls inside a precisely ground cylindrical outer housing. The balls are arranged in a staggered pattern to distribute the load evenly. The ball cage uses a lightweight and high-rigidity machined cage made of light alloy, allowing it to reliably follow high-speed motion. In addition, thrust rings and retaining rings are assembled on both sides of the inner diameter of the outer housing to prevent the ball cage from overrunning.
With this structure, rotary motion, reciprocating motion, and complex motion can be achieved with a low coefficient of friction. The stroke length can be obtained up to twice the range in which the ball cage can move within the outer housing.

Extremely Low Coefficient of Friction
Because the ball and the ball rolling surface are in point contact, which results in minimal rolling loss, and each ball is separated and held by the ball cage, rolling motion is possible with an extremely low coefficient of friction (μ = 0.0006 to 0.0012).

Compact design
Because the cross-sectional shape consists only of a thin outer housing and balls, the bearing's outer diameter can be kept small, resulting in a lightweight, space-saving compact design.

Types and Features

ST Type for Light Load
For light load applications where a large stroke length can be obtained.
Shaft diameter ⌀6 to ⌀100
Also available with seals. ST-UU type

ST-B type for medium load
This is a medium load type with the same dimension as the ST type, a shorter stroke length, and double the rated load.
Shaft diameter ⌀8 to ⌀100
Also available with seals. ST-UUB Type

Cautions and Prohibitions

Handling

(1) Do not disassemble each part. It may cause loss of function.
(2) Do not drop or hit the LM stroke. It may cause injury or damage. In addition, please note that when shock was applied, the product may lose its function even though there is no visible damage to the external appearance.
(3) When handling the product, wear protective gloves, safety shoes, and the like as necessary to ensure safety.

Precautions for use

(1) If a contaminant enters the LM stroke ST type, it may cause abnormal wear or shorten the lifespan. If the ingress of contaminants is anticipated, it is important to select an effective sealing or dust-proof device that matches the operating environment conditions. For the LM stroke ST type, model numbers are available with a special synthetic rubber seal (ST: UU type) that offers excellent abrasion resistance as a dust-proof seal, or a felt seal (ST: DD type) that provides high dust-proof performance with low seal resistance.
(2) If cutting chips or other contaminants adhere to the product, clean it and then reapply lubricant.
(3) Avoid using the product at temperatures exceeding 80°C. If the temperature exceeds this level, resin and rubber parts may be deformed or damaged.
(4) If the product is used in environments where cutting chips, coolant, corrosive solvents, water, or similar substances may enter the interior, please prevent ingress into the product by using bellows, covers, or similar protective measures.
(5) In cases of small stroke, it is difficult for an oil film to form on the contact surfaces between the rolling surface and the rolling element, which may cause fretting. Therefore, please use grease with excellent fretting resistance. In addition, it is recommended to periodically perform a stroke movement approximately equal to the length of the ball cage to form an oil film on the rolling surfaces and rolling elements.
(6) Do not forcibly drive positioning components (such as pins or keys) into the product. This may cause indentations on the rolling surfaces and result in loss of function.
(7) If the shaft is inserted at an angle, there is a possibility of contaminant ingress, damage to internal components, and the rolling element falling out.
(8) Using the product with the rolling element removed may cause early breakage.
(9) If the rigidity and accuracy of the mounting components are insufficient, the load on the bearing will be locally concentrated, and the bearing performance will be significantly reduced. Therefore, please thoroughly consider the rigidity and accuracy of the housing and base, as well as the strength of the fixing bolts.

Rubber seal
(Standard)

Felt seal
(Specified)

Lubrication

(1) Wipe off the anti-rust oil thoroughly and fill with lubricant before use.
(2) Avoid mixing different lubricants. Even if the thickener is the same type of grease, differences in additives and other components may have adverse effects on each other.
(3) When used in special environments such as locations subject to constant vibration, clean rooms, vacuum, or extreme low or high temperatures, please use grease suitable for the specifications and environment.
(4) When lubricating the product, apply lubricant directly to the rolling surface and perform several break-in strokes to ensure grease enters the interior.
(5) The consistency of the grease changes depending on the temperature. Please note that changes in consistency will also affect the sliding resistance of the LM stroke.
(6) After greasing, the mixing resistance of the grease may increase the sliding resistance of the LM stroke. Be sure to perform a break-in operation to allow the grease to fully spread before operating the machine.
(7) Immediately after greasing, excess grease may scatter around the area, so please wipe it off as needed before use.
(8) The properties of grease deteriorate and its lubrication performance declines over time, so it is necessary to inspect and replenish the grease according to usage frequency.
(9) Lubrication intervals vary depending on usage conditions and operating environment. Please determine the final lubrication interval and amount based on actual machine operation.
(10) For lubrication of the LM stroke ST type, both oil lubrication and grease lubrication can be used. Please select the most appropriate type for the given application based on the DN value. For grease lubrication, lithium-soap-based grease No. 2 is recommended.

Storage

Please store the LM stroke indoors, in THK's packaging and shipping configuration, avoiding high temperatures, low temperatures, and high humidity.

Disposal

Please dispose of the product appropriately as industrial waste.