From Chinese Watch Industry Wiki
A pin-lever movement is one featuring an escapement in which the pallets (i.e. the 'fingers' on the lever engaging the escape-wheel) are vertical steel pins rather than the horizontal trapezial jewels of a jewelled-lever movement. Pin-lever movements were once cheaper to manufacture than jewelled-lever and so were generally found in low grade watches.
The myth of the Chinese pin-lever
It is a common misconception that China is, or has been, a major manufacturer of pin-lever watches. For example, some on-line watch reviews include comments along the lines of 'much better quality than the pin-levers that we're used to seeing from this part of the world'. In fact almost all mechanical watch movements made in China have been of the jewelled-lever type. No pin-lever movements or watches have ever been exported from China.
Most likely those who refer to 'Chinese pin-levers' are thinking of watches made in Hong Kong, which was a major centre of watchmaking in the 1960s to 1980s. During this time there was no connection between the Hong Kong and Chinese watch industries. Hong Kong watches mostly used Swiss-sourced movements, often locally assembled. The greatest proportion of these movements comprised pin-levers of the lowest grade from ebauche manufacturers such as Bettlach, Baumgartner, Ronda and Claro-Semag. Prior to 1980, the majority of movements produced in Switzerland, both for local assembly and export as parts, were the pin-lever type. The availability of low-cost quartz watches eliminated all demand for such basic mechanical movements.
Chinese experiments with pin-levers
In the earliest days of the Chinese watch industry, several low-grade wristwatch designs with pin-lever escapements were investigated. China's first home-grown watch in 1955, the Tianjin Wuxing, was based on a Swiss Roskopf-type design. It never entered full production. In 1958, Dongcheng District Watch Factory, Beijing, prototyped a German-influenced design similar to Kienzle and Thiel Brothers. It did not progress beyond a small trial batch under the brand names Tian Tan and Beihai.
The Nanijng Watch Factory developed their own design, seemingly heavily influenced by the Anglo-Celtic calibre TY produced for Smiths and Ingersoll in Britain. The Zijinshan watch was only prototyped as a pin-lever, but entered production with a jewelled-lever escapement. This watch was extensively upgraded to become the highly-successful 9-jewel Zhongshan. As such it was China's lowest grade wristwatch throughout the 1960s to 1990s, yet it was significantly more refined, accurate and reliable than the equivalent low cost watches produced elsewhere in the world.
In 1958, the ZuanShi clock factory put into production a copy of the Anglo-Celtic PY pin-lever pocket-watch. This large, 19th Century style watch achieved a moderate level of production at this and three other factories through the 1960s and 70s. It was not exported. One of those other factories, in Jinan, introduced a more advanced design of no-jewel pocket watch. Again this saw only limited production and was never exported.
The Chinese Ministry for Light Industry seems to have abandoned the notion of very low cost wristwatches by about 1960. Perhaps such watches were recognized to be something of a false economy in a developing nation with no consumer culture but a great shortage of decent watches. The Tongji project of the 1970s effectively enshrined the minimum standards required in a Chinese-designed mechanical watch; fully-jewelled train and jewelled-lever escapement.
Where have all the pin-levers gone?
In the 21st Century, common everyday watches are invariably quartz-driven. A mechanical watch is always purchased as a luxury item; albeit often a very affordable luxury. By contrast, pin-lever is inherently a 'good enough' technology designed to enable the manufacture of the most basic watch at the lowest possible cost; a role now filled by quartz watches. Consequentially there are no surviving pin-lever movement manufacturers anywhere in the world. Most mechanical watch manufacturers currently building in the sub-$1000 category are those who were already making mid-grade fully-jewelled, jewelled-lever watches back before quartz became the norm. This includes all current Chinese mechanical movement makers.
The last survivors
In recent years, some European brands known to be selling Chinese manufactured watches (e.g. Trias and Chevenard) have offered 'Swiss Movement' watches which have been found to contain recently refurbished vintage Swiss Ronda RL-series movements. Some are fully jewelled and feature jewelled-lever escapement, however the majority are pin-levers with one token jewel. The source of these movements is unknown. Some buyers have expressed disappointment due to their mistaken expectation that a 'Swiss Movement' was a guarantee of a superior grade of movement compared to a Chinese movement. Accusations have been made that the watches are falsely labelled, however such accusations are incorrect. The movements really are Swiss.
Where a low-cost new watch is offered with a certified 'Swiss' mechanical movement, but with no jewel-count specified, and no view of the movement offered, it is wise to assume the watch contains a refurbished vintage Swiss pin-lever.