RunRight RT F tensioners are designed for front mounting applications where access to back side or rear mounting surfaces is not possible. A single threaded hole is required to mount these tensioners. These tensioners include a special mounting screw and spacer bushing. They are manufactured with powder metal or cast iron housings, cast iron arms and inner square, come with the standard Tensys™ 10 rubber inserts, and can be used for applications operating within a -40° to 180°F (-40° to 80°C) temperature range.

Unit of Measure





N/A Chain/Belt Tensioner

Element Material

N/A Natural Rubber


N/A Elastomeric


N/A Blue

UPC Number

N/A 53281

Dimensional Data


N/A RT F45

Mounting Bolt Size

N/A M20

Outside Diameter (Dim D)

N/A 4.53 in115 mm

Overall Length (Dim E)

N/A 7.87 in200 mm

Idler Bolt Size

N/A 3/4 - 10 x 6

Dimension L

N/A 10.24 in260 mm

Dimension J-1

N/A 8.86 in225 mm

Dimension J-2

N/A 7.09 in180 mm

Dimension M

N/A 1.26 in32 mm

Dimension R

N/A 0.94 in24 mm

Dimension G

N/A 0.47 in12 mm

Dimension O

N/A 0.71 in18 mm

Dimension P

N/A 0.49 in12.5 mm

Dimension K

N/A 2.76 in70 mm

Cubic inches

N/A 365.06726 in³

Performance Data

Normal Temperature Range

N/A -40 to 180 ºF-40 to 80 ºC

Force at 20° Angle of Pretension (Normal Force Level) (Dimension F)

N/A 292.5 lb1300 N

Distance at 20° Angle of Pretension (Normal Force Level) (Dimension S)

N/A 3.1 in78 mm



  • The recommended angle of pretension is 20°. This provides the tensioner a maximum capability to absorb vibrations and shock loads, while also maintaining a range of motion to address the system’s belt or chain stretch.
  • Mounting accessories into the “Hard” Position results in approximately 25% higher tensioning force over the “normal” position.
  • Inch (imperial) standard tensioner units all come with both the mounting screw and a zinc-plated idler bolt with nuts.