Replacing friction discs on TOS Trenčín lathes

Replacing clutch and brake friction discs on TOS Trenčín / TRENS lathes

Worn friction discs on TOS SN series lathes can cause slipping, inconsistent engagement and unreliable operation of the feed and drive mechanisms. Over time, the friction surfaces, levers and locking blocks become worn, which affects smooth operation and can lead to increased wear of surrounding components.

Correct replacement of the friction discs and related parts is essential for restoring proper engagement and maintaining reliable machine performance. In this article, we will look at the friction disc system used on TOS Trenčín / TRENS lathes SN, SM and SUI models, explain the most common signs of wear and show the main components involved in the replacement process.

Damaged friction discs

See the next picture for damaged clutch friction discs on an SN50. You can observe two types of damage:

grooves or scratches
burns

The grooves on the frictions discs occurred because of impurities and small particles in the oil in the speed gearbox. That is caused by usage of old oil.

The burn on the friction discs comes from the lack of oil in the speed gearbox, the lathe was running dry for some time.

This is why it is crucial to change regularly the oils in your gearboxes in accordance with the owner’s manual.

Brake friction discs 803220 & 803222

The brake friction discs 80322 (internal) and 803220 (external) are interchangeable between TOS Trenčín / TRENS lathes. See table bellow for the suitable lathes and required quantities.

Brake discs	Required amount
SN32	6 external + 5 internal
SN40, SN45, SN50	6 external + 5 internal
SN55, SN63, SN71	7 external + 6 internal
SM16	6 external + 5 internal
SUI32	7 external + 6 internal
SUI40, SUI50	7 external + 6 internal

Brake / clutch friction discs 803217 & 803221

The friction discs 80321 (internal) and 803217 (external) can be used both as brake discs as well as clutch discs depending on the lathe model. See table bellow for the suitable lathes and required quantities.

Clutch discs	Required amount
SN32	14 external + 16 internal
SN40, SN45, SN50	14 external + 16 internal
SN55, SN63, SN71	14 external + 16 internal
SM16	14 external + 16 internal
SUI32	14 external + 16 internal

Brake discs	Required amount
SN400, SN500	7 external + 6 internal
SN630, SN710	7 external + 6 internal

Clutch friction discs 703080 & 703081

The clutch friction discs 703081 (internal) and 703080 (external) are interchangeable between TOS Trenčín / TRENS lathes. See table bellow for the suitable lathes and required quantities.

Clutch discs	Required amount
SN55, SN63, SN71	14 external + 16 internal
SN400, SN500	14 external + 16 internal
SN630, SN710	14 external + 16 internal
SUI40, SUI50	14 external + 16 internal

Clutch levers

Required amount of levers for the clutch is 24 pieces.

See compatibility of clutch levers for TOS Trenčín / TRENS lathes bellow in the table.

See links for the levers on our eshop:

803214	803211
SN32	SN55, SN63, SN71
SN40, SN45, SN50	SN400, SN500
SM16	SN630, SN710
SUI32	SUI40, SUI50

Clutch blocks

Required amount of blocks for the clutch is 2 pieces.