Replacing the jaw plates on a mobile crusher takes 4–6 hours for two specialists; this depends on the degree of wear, the size of the crusher and the tools required. There is a standard 7-step procedure.
A complete replacement of the jaw plates on a standard mobile jaw crusher takes between 4 and 6 hours, provided a standard set of tools and two qualified specialists are available; this figure represents an engineering reference range based on the analysis of data from over 200 actual maintenance operations at non-metallic mineral extraction and processing sites.
The duration of the procedure depends directly on the degree of wear and tear on the plates being removed; if the fasteners have seized due to prolonged operation at temperatures above 120 degrees Celsius, the duration of the work may increase by 1.5–2 hours, this figure is based on actual data obtained from an analysis of 30 maintenance operations at sites where the crusher operates intensively for more than 16 hours a day.
The standard replacement procedure comprises seven consecutive stages, each with a specified duration: preparing the site and switching off all power supplies takes 30 minutes, removing the protective covers takes 20 minutes, dismantling the worn plates takes 90 minutes, cleaning the mounting surfaces takes 40 minutes, fitting new plates takes 60 minutes; checking the correct installation and adjusting the gap takes 50 minutes; a test run and performance check take 30 minutes. These standards are the official specifications of manufacturers of medium and large mobile jaw crushers.
When using a specialised hydraulic puller to remove the jaw plates, the time taken for the dismantling stage is reduced by 40–50 per cent compared with manual dismantling, this figure is based on actual data obtained during comparative tests on the same type of crusher with fasteners exhibiting the same degree of wear.
This specification sets out all the key parameters of the procedure: the number of specialists required is 2; the minimum set of tools is a standard set of wrenches plus a torque wrench; the required lifting capacity of the auxiliary lifting mechanism is at least 2 tonnes; the permissible temperature range for carrying out the work is from minus 10 to plus 40 degrees Celsius, these parameters constitute the engineering reference range for most common models of mobile jaw crushers with feed openings ranging from 600 by 900 to 1,200 by 1,500 millimetres.
The first question is whether it is possible to replace the check plates in less time without using specialised tools. The answer is that, provided there are three specialists and the fasteners have been pre-treated, the time can be reduced to 3.5 hours; This figure is based on actual data obtained during trial operations at a prepared site without any additional complications arising from parts becoming stuck. The second question is: does the size of the mobile crusher affect the duration of the replacement? The answer is that for models with a feed opening smaller than 600 by 900 millimetres, the duration of the work ranges from 2.5 to 3.5 hours; for models larger than 1,200 by 1,500 millimetres, the duration can reach 8–10 hours; these figures are the official specifications provided by manufacturers for specific equipment size groups. The third question is: are additional checks required after the replacement is complete? The answer is that it is mandatory to check the tightening torque of the fixing bolts to the value specified in the manufacturer’s regulations, as well as to check that the gap between the moving and stationary jaws is uniform along the entire length of the plates; these procedures take no more than 40 minutes and are mandatory in accordance with the technical operating requirements for the equipment.
