SIT Motor Bases
Adjustable motor bases and slide rails for belt tensioning and variable-speed drives: Compatta TC, Varex TX, Linea TT, TV909, TV910 and TB911.
SIT Motor Bases
A motor base carries the electric motor and lets it slide to set the belt tension and centre distance of a belt drive, or to vary the speed of a variable-speed pulley drive. SIT supplies six motor base families: galvanised steel bases and rails for belt tensioning, and cast-iron bases with handwheel adjustment for precise speed variation. Correct tension set with the motor base can be checked with a TEN-SIT belt tension meter and the alignment with the LINE-LASER.
| Family | Material | Main use | Motor frame sizes |
|---|---|---|---|
| Compatta TC | Galvanised steel | Belt tensioning, low height | 56 - 225 |
| Varex TX | Galvanised steel | Variable-speed pulley drives | 56 - 132 |
| Linea TT | Galvanised steel | Universal motor slide rails, almost any position | 56 - 400 |
| TV909 | Cast iron | Precise speed variation, handwheel | - |
| TV910 | Cast iron | Speed variation where height is limited | - |
| TB911 | Cast iron and steel | Pivoting adjustment / tensioning in tight spaces | - |
Compatta TC motor bases
The COMPATTA motor base is very easy to install, suits any motor type and has a reduced height. The setting is adjusted with a spanner without loosening the motor bolts and without losing the drive alignment, over a wide adjustment range. Galvanised steel; stainless steel and customised motor bases on request. Six sizes are available from stock.
Part number example: TC MEDIA.
| Model | Motor frame | Motor power 2-pole (kW) | Motor power 4-pole (kW) | Max. adjustment (mm) | Weight (kg) |
|---|---|---|---|---|---|
| TC 80 (mignon) | 56 - 80 | 0.12 - 1.1 | 0.1 - 0.75 | 63 - 98 | 1.5 |
| TC 90 (piccola) | 71 - 90 | 0.37 - 2.2 | 0.25 - 1.5 | 90 - 118 | 2.0 |
| TC 112 (junior) | 80 - 112 | 0.75 - 4 | 0.55 - 4 | 105 - 169 | 3.5 |
| TC 132 (media) | 90 - 132 | 1.5 - 9 | 1.1 - 7.5 | 132 - 208 | 5.8 |
| TC 180 (maxi) | 160 - 180 | 15 - 25 | 11 - 22 | 151 - 176 | 12.0 |
| TC 225 (magnum) | 200 - 225 | 30 - 45 | 30 - 45 | 144 - 182 | 22.5 |
Max. adjustment depends on the motor frame (larger frame = shorter stroke). 2-pole = 2,800 rpm, 4-pole = 1,400 rpm.
Varex TX motor bases
VAREX motor bases (galvanised steel) are an economical solution for variable-speed systems with a variable-speed pulley: the axial displacement of the electric motor gives continuous speed variation of the driven shaft. Fixed with six holes to the base.
Part number example: TX MEDIA.
| Model | Motor frame | Motor power 2-pole (kW) | Motor power 4-pole (kW) | Max. adjustment (mm) | Weight (kg) |
|---|---|---|---|---|---|
| TX (mignon) | 56 - 80 | 0.12 - 1.1 | 0.1 - 0.75 | 63 - 98 | 2.8 |
| TX (piccola) | 71 - 90 | 0.37 - 2.2 | 0.25 - 1.5 | 90 - 118 | 4.0 |
| TX (media) | 90 - 132 | 1.5 - 9 | 1.1 - 7.5 | 132 - 208 | 10.0 |
Linea TT motor slide rails
The universal LINEA range (galvanised steel) allows mounting and adjustment of all types of electric motors in almost all positions (for upside-down mounting, consult the technical department). The strong construction and special fixing elements allow all combinations of the adjusting threaded elements, and the rails can be bolted to the foundation or welded to a steel base. Stirrup type A for frames up to 112, type B from frame 100 to 400.
Part number example: TT 100/10.
| Model | Stirrup type | Motor frame | Rail length A (mm) | Weight (kg) |
|---|---|---|---|---|
| TT71/6 | A | 56 - 71 | 312 | 2.4 |
| TT80/8 | A | 80 | 375 | 2.7 |
| TT90/8 | A | 80 - 90 | 395 | 4.3 |
| TT100/10 | A | 100 | 395 | 4.4 |
| TT112/10 | A | 100 - 112 | 495 | 5.2 |
| TT132/10 | B | 100 - 132 | 530 | 7.8 |
| TT160/12 | B | 160 | 630 | 8.8 |
| TT180/12 | B | 160 - 180 | 700 | 12.0 |
| TT225/16 | B | 200 - 225 | 864 | 20.4 |
| TT280/20 | B | 250 - 280 | 1,072 | 43.0 |
| TT355/24 | B | 315 - 355 | 1,330 | 52.0 |
| TT400/30 | B | 400 | 1,430 | 58.0 |
TV909 cast-iron motor bases
TV909 motor bases (cast iron) give speed variation through axial displacement of a motor fitted with a variable-speed pulley. Their rigidity and fine handwheel-screw adjustment suit applications where the driven-shaft speed must be set very precisely. Sliding runs on two generously sized dovetail guides; to fix the base, move the top plate with the handwheel to uncover the fixing holes.
Part number example: TV909 G2.
| Model | Length A (mm) | Max. adjustment (mm) | Weight (kg) |
|---|---|---|---|
| TV909 G1 | 332 | 98 | 6.7 |
| TV909 G2 | 400 | 158 | 13.6 |
| TV909 G3 | 568 | 217 | 24.5 |
TV910 compact cast-iron motor bases
TV910 motor bases have the same technical characteristics as the TV909 with a reduced thickness for compact installations. The handwheel sits on top of the tail support and drives the adjusting screw through a universal joint for backlash-free transmission; with the handwheel above the base, they fit where space does not allow other motor bases.
Part number example: TV910 G2.
| Model | Length A (mm) | Max. adjustment (mm) | Weight (kg) |
|---|---|---|---|
| TV910 G1 | 345 | 78 | 6.1 |
| TV910 G2 | 420 | 131 | 8.9 |
| TV910 G3 | 475 | 171 | 14.5 |
TB911 adjustable pivot-plate motor bases
TB911 bases (cast iron and steel) are designed for speed-variation drives with a variable-speed pulley where the motor can only be moved by pivoting. A jointed fixing plate and a jointed handwheel screw system, held by jointing axes and double pillow blocks, give a rigid mounting. They can also be used for belt tensioning between motor and driven machine where conventional motor bases do not fit.
Part number example: TB 1.
| Model | Length A* (mm) | Weight (kg) |
|---|---|---|
| TB 1 | 413 | 9.4 |
| TB 2 | 548 | 20.0 |
* With 90° between handwheel axle and base.
Full dimension tables (all mounting dimensions) are available on request. Source: SIT S.p.A. catalogue "Pulleys and components", pp. 157 - 162. Brand names are used for identification and technical reference.
Request a Quote Ask an Engineer All belt drive regulation products
Available on request
Specific series are being qualified with our manufacturing partners. Send your requirement and our engineers will propose a solution.
What we need to select the right product
Motor power and speed, required ratio, center distance, duty and operating hours, existing belt profile and length.
Typical applications: Fans, pumps, compressors, crushers, screens and machine drives.
Original, alternative or custom
Depending on the requirement we offer original-brand products, selected supply from qualified manufacturers, replacement solutions or custom-engineered designs. Each product shows MECHATRIC's relationship to it.
Original Brand & EquivalentSelected SupplyReplacement SolutionCustom Engineered