While many linear applications are relatively short to moderate in length (12 feet or shorter), there are applications that require travel lengths in the 40 to 50-foot range, and sometimes longer. PBC Linear offers a variety of products that fulfill these various long-length requirements, including several options that can join rails end to end. Where longer travel requires butting rails end to end, we recommend a rolling element (wheel, ball, etc.).
Gliding Surface Linear
PBC Linear often gets inquiries from customers interested in the plain bearing feature of our Gliding Surface Technology in order to solve their long travel applications. Some specific products within this family includes Uni-Guide, Low Profile Uni-Guide, and Mini Rail. In addition, our ceramic coated shafting, also known as aluminum feather shafting, and ceramic coated rail, or feather rail, both fall under the gliding surface category.
Corrosion resistance and light weights are attractive features for these product lines. Although all of them are excellent products and great choices for a wide range of applications, they do not lend themselves well for end joining. The simple reason is that linear plain bearings and carriages that employ plain bearing technology have a precise running clearance for which alignment is critical, and these end joints have a high probability for binding due to misalignment. Also, the carriages for Uni-Guide, Low Profile Uni-Guide, and Mini-Rail are matched to the rail, making the addition of rails problematic.
As previously mentioned, the product families that contain wheels, rollers, or balls are the best candidates to transition a joint along a rail/raceway. We will explore some of those product families that are suited for long-lengths, starting with Roller Pillow Blocks and following with Redi-Rail, Hevi-Rail, and IVT linear guides.
Roller Pillow Blocks
Roller Pillow Blocks use round shafting as the raceway. Large cam followers in the roller pillow block deliver industrial strength performance over long travel lengths while excelling in dirty environments. For very long runs, we recommend the hardened steel or hardened stainless steel shaft be supported by the aluminum support rail. The shaft and support rail assembly (SRA) can be butt joined for long runs, and the low-friction rollers easily navigate joined or misaligned shafts, accounting for any shaft deflection.
- Maximum continuous length for one rail: 15 feet (4.57 meters).
- End joining: low-friction rollers will absorb moderate misalignment and shaft deflection.
An example of roller pillow block implementation can be found in a cryogenic storage and retrieval application.