The Union 3R35 is a mortice deadlock latch which forms part of the C-Series range of mortice locks that have been fitted to homes and businesses for decades. Originally made by Chubb, you may find these feature the distinctive Chubb brand when replacing an old lock. This product is identical and just features the new Union branding.

These locks have a distinctive upright design and feature detainers, rather than levers. While they offer a high level of security they do not meet the requirements of British Standard BS3621:2007. Detainer locks generally feature a higher number of key combinations that lever locks.

In line with a number of other mortice locks, these locks feature a silver lock case but they have unique measurements that identify them from other mortice locks. Please refer to the line drawing for details.

Please note that this lock is also available as the 3R35X which is the escape version of the lock, where the inside handle cannot be locked, allowing escape in the event of emergency. Search for “3R35X” to find this lock.

The deadlocking latch on this lock throws 10mm.

When the door is closed, the automatic deadlocking latch will engage in the strike to keep the door closed.

It is retracted with the key and the hold back snib can be used to hold the latch back.

This lock is supplied with a security striking box in a grey finish.

Suitable for use on doors up to 50mm thick. The thickness of the door is determined by the length of the keys. If you require this lock to be fitted to a very thick door, we may be able to supply extra long keys. Please contact us for more details.

These locks are handed so please select the hand that you require from the table. If you are stood outside, the door is hinged on the left and the door opens outwards, select a left hand. If the door is hinged on the right, select the right hand. If the door opens inwards, reverse these instructions.

Supplied with 2 brass keys as standard. We can cut additional keys for this lock, just select whether you’d prefer genuine or copy key blanks and the quantity required from the associated products on this page.

Should you require more than one lock to work on the same set of keys, these locks can be keyed alike by our inhouse locksmith team. We can typically dispatch the same day (larger quantities may require longer).

We stock a range of associated parts to these locks, including key blanks, rebate sets for use on double doors and levers. Please select the products you require from the associated products on this page.

These locks are not suitable for use on fire doors.

Union have manufactured high-quality, British designed locks and door hardware for more than 180 years. While their brand has evolved and grown to include a larger family of products over time, they all share a common purpose: a commitment to first class quality and design, with products that make the lives of their customers easier.

From humble beginnings in 1840, Union has grown from a family business to become a leader in British designed locks and door hardware around the world. They started in Willenhall, the heart of the British lock-making industry in the 19th Century. Today, Willenhall is home to their state-of-the art manufacturing facility and headquarters – an area steeped in heritage and history for the locks and door hardware industry.

Detainer mortice locks operate in a similar way to their lever counterparts, but operate using a detainer. The way that they work is similar, in that the moving element of the detainers is blocked until they are all aligned, but the “gate” that is found on a lever is located in a different place. This makes them difficult to pick and more less susceptible to destructive entry.

Mortice lever locks (sometimes called mortise locks) are commonly fitted to wooden doors but can also be found used in steel, aluminium, and composite doors. They are locked from both the inside and outside with the key which throws the deadbolt. By definition, a mortice lock is fitted (“morticed”) within the door, rather than being fitted to the face or surface of it.

There are multiple types of lever lock in use in the UK. Dead locks (mortice dead locks) are operated by a key only whereas sash locks (mortice sash locks) feature a dead bolt and a latch which is operated by a handle (often a lever handle). Both lever locks with throw the dead bolt into a strike plate. The strike plate on sash locks also accepts the sprung loaded reversible latch.

Lever mortice deadlocks can be used for fitting to front or back doors and to internal doors and external doors, but we’d always recommend fitting a British Standard BS3621 product to external doors for maximum security. You should also check with the houseowner’s insurer’s requirements on both residential properties and commercial properties. You may find lever locks fitted to commercial properties but cylinder lock cases operated by a cylinder or pin tumbler lock are more common mortice locks fitted in commercial environments.

Lever mortice door locks are commonly used for internal doors too. These tend to be 3 lever mortice locks where the requirements for security and burglary prevention are lower.

When replacing an existing lever mortice lock, you may find that your replacement mortice lock is larger than the one that you are replacing. This may be because you are improving security, such as upgrading to a lock with thicker, anti-drill hard steel plates or because the forend length, forend width or the design of the lock has changed. The hole for the lock can normally be made larger with a hammer and chisel. This can also be the case for strikes, which may have changed design.

When fitting a lever mortice lock to new timber doors, we’d recommend using Souber’s DBB morticer for quick results. You can find the DBB1 morticer here: https://www.duffells.com/souber-dbb-mk2-mortice-jig.html.

Please always ensure that your door is sufficiently thick to accommodate the mortice lock that you are fitting. The Master Locksmith Association recommend a minimum thickness of 44mm.

A lever mortice lock prevents a door from opening by throwing a bolt from the lock into a metal keep or strike, fitted to the frame. Once the bolt is engaged in the keep, a hinged door is prevented from being opened. A mortice lock bolt is locked or unlocked from either the inside or outside by a key. Inside the lock, there is space for the bolt to be retracted. If the cuts in the key match the levers inside the lock, the user will be able to turn the key to throw (to lock) or withdraw (to unlock) the bolt. If the wrong key is used, the levers will not line up and the lock will not operate.

Duffells stocks a huge range of mortice locks at all levels of security. All of our lever mortice door locks are available for delivery in as little as 24 hours. We offer a range of express delivery options as well as standard delivery and you can find delivery details on our thousands of products on our delivery info page.