External cover for liquefied gas storing tank

The utility model discloses a lubricating device, which is used for a concrete conveying pump. One hydraulic oil pipe is communicated with a left hydraulic oil chamber of a lubricating grease pump and the other hydraulic oil pipe is communicated with a right hydraulic oil chamber of the lubricating grease pump. A lubricating grease box is communicated with a left grease chamber of the lubricating grease pump, and the left grease chamber is communicated with a left oil inlet of a two-way valve. One end of the left oil inlet is communicated with a pressure-regulating valve through a first one-way valve in the two-way valve, and the other end is communicated with at least one lubricating point. The lubricating grease box is communicated with a right grease chamber of the lubricating grease pump, and the right grease chamber is communicated with the right oil inlet of the two-way valve. One end of the right oil inlet is communicated with the pressure-regulating valve through a second one-way valve in the two-way valve, and the other end is communicated with the other lubricating point. The utility model is the lubricating device which can carry out timing and fixed-point lubrication to lubricating points which need being lubricated, and the lubricating points which need not be lubricated can not be carried out lubrication temporarily. The utility model has the advantages of service life of moving parts prolonging and dosage saving of lubricating grease.